Electroless copper plating additive, electroless copper plating solution and method for electroless copper plating of IC carrier board

Abstract

The present invention discloses a chemical copper plating additive, a chemical copper plating solution and a method for chemical copper plating of an IC carrier board, which relates to the technical field of IC carrier board production and manufacturing. The chemical copper plating additive is composed of the following components by mass fraction: 0.5 - 3.0% of a complexing agent, 0.5 - 3.0% of a reducing agent, 0.2 - 2.0% of an accelerator, 0.5 - 3.0% of a stabilizer, 0.2 - 2.0% of a wetting agent, and the balance is water. The chemical copper plating additive of the present invention can effectively improve the stability of the chemical copper plating solution, and the uniformity, adhesion and deposition rate of the coating are good. The deposition rate and the degree of overplating can meet the production of chemical copper plating of IC carrier boards.

Description

Technical Field

[0001] The present invention relates to the technical field of IC carrier board production and manufacturing, and particularly relates to a chemical copper plating additive, a chemical copper plating solution, and a method for chemical copper plating of an IC carrier board. Background Art

[0002] IC substrate products are different from traditional printed circuit boards (PCBs). High processing difficulty and high investment threshold are the two core barriers of packaging substrates. From the dimensions of the number of product layers, board thickness, line width and line spacing, and minimum annular width, etc., IC substrates tend to be more precise and miniaturized. They are a more high-end type of PCB and can play a key role in supporting, connecting, dissipating heat, and protecting chips.

[0003] There are multiple technical difficulties in the production process of IC carrier boards, which are mainly reflected in four aspects: pattern formation, copper plating, solder resist process, and surface treatment. Among them, electroless copper plating is one of the important processes for metallizing non-metallic materials. Especially in the fields of PCBs and carrier boards, the electroless copper layer is used as a conductive seed layer to facilitate the thickening of the metal layer in subsequent processes. Electroless copper plating is different from electroplating process. Electroless copper plating does not require metal deposition under an external current, and there will be no problem of uneven distribution of power lines on the surface of the plated parts during the reaction process. The dispersion ability of the electroless copper plating solution is very strong, and a uniformly structured coating can be deposited on the surface of plated parts with complex structures and uneven surfaces. Therefore, electroless copper plating has a wide range of applications in different fields.

[0004] The process flow of electroless copper plating is generally: swelling → degumming → pre-neutralization → neutralization → degreasing → micro-etching → pre-impregnation → activation → reduction → electroless copper plating. Electroless copper plating is essentially an oxidation-reduction reaction of copper ions on the surface of non-metallic substrates, and the reaction usually requires a catalyst to proceed. Under the action of the catalyst and reducing agent on the substrate surface, the copper complex dissociates, and the copper ions gain electrons and are reduced to copper atoms, forming a metal copper crystal layer on the surface. The electroless copper plating system using formaldehyde as a reducing agent is the most widely used at present, but there are also other systems using sodium hypophosphite, etc. as reducing agents.

[0005] At present, there are already some technical solutions related to electroless copper plating. For example, Patent CN 102277567 A discloses an electroless copper plating solution for microhole filling, whose components include copper sulfate pentahydrate, ethylenediaminetetraacetic acid, formaldehyde or glyoxylic acid, a mercapto heterocyclic compound, a polyether with an average molecular weight of 3650, sodium hydroxide and an appropriate amount of distilled water, realizing the electroless copper plating filling of microholes without voids and seamless. Patent CN 105200402 A provides an electroless copper plating solution, which contains a copper salt, a reducing agent, a complexing agent, a pH regulator, an optional stabilizer and an optional surfactant. The electroless copper plating solution contains 2-mercaptobenzothiazole and R1-SH, where R1 is an alkyl group with 8 - 14 carbon atoms, which can effectively alleviate the overplating phenomenon, and when using this electroless copper plating solution for electroless copper plating, it has a high plating rate and adhesion. Patent CN 112111731 A introduces an electroless copper plating solution, its preparation method and application, and a metal copper grid with a line width of 3 - 5 μm can be formed by chemical deposition method. The formed metal copper grid structure is dense, the copper surface is flat, there are no problems of cracks and broken wires, there is no copper powder between the grid and the circuit, and the bonding force between the copper film and the substrate is good, without falling off phenomenon. Patent CN 115261831 A also discloses a preparation method of an economical and environment-friendly electroless copper plating solution, which is used to solve the problems that the existing electroless plating solution contains formaldehyde, and the deposition rate is low and the stability is not high.

[0006] The existing electroless copper plating technology has made great research progress in solving the problem of gaps in microhole filling and realizing the environmental protection of the plating solution. However, with the development of the thinning and localization of the carrier board, there is a huge demand for carrier board production in the domestic market. Due to the very strict requirements for the process size precision, quality, specifications, etc. of the carrier board, in such a very small space, the electroless copper plating interconnection process will become more demanding. The diffusion and adsorption behaviors of the additives used in the previous plating solution will change in such a confined space, which will surely be unfavorable for obtaining a densely grown copper layer in such a confined space. There are still many defects in the existing technical solutions for the production of carrier boards. Therefore, in order to adapt to the development of integrated circuits, it is urgent to develop an electroless copper plating additive suitable for IC carrier boards, reduce the defect rate in the production process, and meet the production requirements of the carrier board for electroless copper plating. Summary of the Invention

[0007] To solve the above technical problems, the present invention provides an electroless copper plating additive suitable for IC carrier boards, its preparation method and application. Specifically, it is realized through the following technical solutions.

[0008] Provide an electroless copper plating additive, which is composed of the following components by mass fraction:

[0009] Complexing agent 0.5 - 3.0%,

[0010] Reducing agent: 0.5 - 3.0%,

[0011] Accelerator: 0.2 - 2.0%,

[0012] Stabilizer: 0.5 - 3.0%,

[0013] Wetting agent: 0.2 - 2.0%,

[0014] The balance is water;

[0015] The structural formula of the complexing agent is as follows:

[0016] ;

[0017] where n is 4 or 6 or 8.

[0018] Preferably, the reducing agent is selected from at least one of 3,5-dichlorosalicylaldehyde (CAS No.: 90 - 60 - 8), 4,6-dichlorosalicylaldehyde (CAS No.: 78443 - 72 - 8), 4,5-dichlorosalicylaldehyde (CAS No.: 84388 - 68 - 1).

[0019] Preferably, the accelerator is selected from at least one of cyclopropyl phenyl sulfide (CAS No.: 14633 - 54 - 6), cyclobutyl phenyl sulfide (CAS No.: 67132 - 84 - 7), 2-nitrodiphenyl sulfide (CAS No.: 4171 - 83 - 9).

[0020] Preferably, the stabilizer is selected from at least one of 3-mercapto-N-methyl-propionamide (CAS No.: 52334 - 99 - 3), 3-mercapto-N-nonylpropionamide (CAS No. 228716 - 16 - 3), 6-mercaptopyridine-3-sulfonamide (CAS No.: 10298 - 20 - 1).

[0021] Preferably, the wetting agent is selected from at least one of 3,5-dihydroxybenzohydrazide (CAS No.: 7732 - 32 - 3), 3,4-diaminobenzohydrazide (CAS No.: 103956 - 09 - 8), 3-amino-4-hydroxybenzohydrazide (CAS No.: 7450 - 57 - 9).

[0022] Preferably, the preparation method of the complexing agent is as follows:

[0023] Per 100 parts by weight, 4 - 6 parts of catechol (CAS No.: 128 - 80 - 9), 0.8 - 1.2 parts of potassium carbonate (CAS No.: 584 - 08 - 7), 0.4 - 0.6 parts of potassium iodide (CAS No.: 7681 - 11 - 0), 4 - 6 parts of 2 - chloroethoxyethanol (CAS No.: 628 - 89 - 7) and 25 - 35 parts of acetonitrile (CAS No.: 75 - 05 - 8) are added into a reaction vessel and heated at 65 - 70 °C for 1 - 2 hours;

[0024] Then, 4 - 6 parts of 4 - dimethylaminopyridine (abbreviation: DMAP; CAS No.: 1122 - 58 - 3), 0.8 - 1.2 parts of triethylamine (abbreviation: Et3N; CAS No.: 121 - 44 - 8), 1.5 - 2.5 parts of 1,2 - dichloroethylene (CAS No.: 540 - 59 - 0), 0.8 - 1.2 parts of p - toluenesulfonyl chloride (abbreviation: TsCl; CAS No.: 98 - 59 - 9) are added and heated at 75 - 80 °C for 3 - 4 hours;

[0025] 0.4 - 0.6 parts of ethanol (CAS No.: 628 - 89 - 7) and 0.8 - 1.2 parts of toluene (CAS No.: 108 - 88 - 3) are added as solvents, then 4 - 6 parts of alkane dithiol and the balance of water are added, heated at 85 - 90 °C for 5 - 6 hours and then cooled to room temperature, and the complexing agent is obtained by extraction with dichloromethane (CAS No.: 75 - 09 - 2) and water.

[0026] The alkane dithiol described above is selected from 1,4 - butanedithiol (CAS No.: 1191 - 08 - 8), 1,6 - hexanedithiol (CAS No.: 1191 - 43 - 1) or 1,8 - octanedithiol (CAS No.: 1191 - 62 - 4).

[0027] In some specific embodiments, the preparation method of the complexing agent is as follows:

[0028] Per 100 parts by weight, 5 parts of catechol, 1 part of potassium carbonate, 0.5 part of potassium iodide, 5 parts of 2 - chloroethoxyethanol and 30 parts of acetonitrile are added into a reaction vessel and heated at 65 °C for 1 hour;

[0029] Then, 5 parts of 4 - dimethylaminopyridine, 1 part of triethylamine, 2 parts of 1,2 - dichloroethylene, 1 part of p - toluenesulfonyl chloride are added and heated at 75 °C for 3 hours;

[0030] 0.5 part of ethanol and 1 part of toluene are added as solvents, then 5 parts of alkane dithiol and the balance of 43 parts of water are added, heated at 85 °C for 5 hours and then cooled to room temperature, and the complexing agent is obtained by extraction with dichloromethane and water.

[0031] In the electroless copper plating additive of the present invention, the complexing agent can undergo a complexation reaction with copper ions to form a complex, which can not only improve the stability of the electroless copper plating solution, prevent secondary hydrolysis to generate copper hydroxide, but also improve the quality of the plated copper crystals. At the same time, it has the effect of accelerating electroless copper plating and increasing the deposition rate of copper plating. The role of the reducing agent is to reduce the copper ions in the formed complex to metallic copper. Most of the reducing agents used in current PCB production are basically formaldehyde, which is extremely harmful to the human body. The present invention uses salicylaldehyde derivatives as the reducing agent, greatly reducing the harm caused by formaldehyde. The accelerator can effectively control the deposition rate during the electroless copper plating process and accelerate the electroless copper plating rate. The stabilizer can prevent the formation of small copper crystals during the electroless copper plating process, improve the uniformity of electroless copper plating, and at the same time, the stabilizer can also improve the stability of the electroless copper plating solution and the service life of the plating solution. The wetting agent can inhibit the generation of hydrogen during the electroless copper plating process, which causes bubbles on the surface of the plated copper film, thereby avoiding the occurrence of hydrogen embrittlement.

[0032] The present invention also provides an electroless copper plating solution containing the above-mentioned electroless copper plating additive.

[0033] Preferably, the electroless copper plating solution is composed of the following components by mass fraction: 4 - 6% of copper sulfate, 4 - 6% of the electroless copper plating additive, and the balance is water.

[0034] The present invention also provides an electroless copper plating method for an IC carrier board, including an electroless copper plating process: immersing the IC carrier board in the above-mentioned electroless copper plating solution at 50 ± 0.2 °C for 35 - 45 minutes.

[0035] Preferably, an activation process is also included before the electroless copper plating process; the activation process is specifically: immersing the IC carrier board in the activation tank solution at 25 ± 5 °C for 3 ± 1 minute; the activation tank solution contains 3% hydrochloric acid and 5% palladium chloride by mass fraction, and the balance is DI water.

[0036] The electroless copper plating additive of the present invention contains five active ingredients: a reducing agent, an accelerator, a stabilizer, a wetting agent, and a complexing agent, which can effectively improve the stability of the electroless copper plating solution, and the uniformity, adhesion, and deposition rate of the coating are good. The deposition rate and the degree of overflow plating can meet the production of electroless copper plating for IC carrier boards. Description of the Drawings

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0038] Figure 1Reaction formula for preparing complexing agent in the embodiments of the present invention;

[0039] Figure 2 Effect diagram of the IC substrate slice after electroless copper plating in Embodiment 1 of the present invention;

[0040] Figure 3 Effect diagram of the IC substrate slice after electroless copper plating in Comparative Example 11 of the present invention. Detailed implementation manners

[0041] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0042] The reaction formula for preparing the complexing agent in the following embodiments is as Figure 1 shown. The specific preparation method is as follows: Based on a total of 100 parts by weight of raw materials added to the three-necked flask, add 5 parts of catechol, 1 part of potassium carbonate, 0.5 part of potassium iodide, 5 parts of 2-chloroethoxyethanol, and 30 parts of acetonitrile to the three-necked flask, and heat at 65 °C for 1 hour; then add 5 parts of 4-dimethylaminopyridine, 1 part of triethylamine, 2 parts of 1,2-dichloroethylene, and 1 part of p-toluenesulfonyl chloride, and heat at 75 °C for 3 hours; add 0.5 part of ethanol and 1 part of toluene as solvents, then add 5 parts of alkane dithiol (where the number of carbon atoms n of the alkane can be 4, 6, 8) and the remaining 43 parts of water, heat at 85 °C for 5 hours and then cool to room temperature, and extract with dichloromethane and distilled water multiple times to obtain the complexing agent.

[0043] Embodiment 1

[0044] Weigh the reducing agent, accelerator, stabilizer, wetting agent, complexing agent, and distilled water according to the following mass concentration formula and add them to the reaction kettle in sequence, and stir and mix at room temperature for 30 minutes to obtain the electroless copper plating additive of this embodiment, and store it sealed for later use.

[0045] The concentration of the reducing agent is 1.5%, specifically 3,5-dichlorosalicylaldehyde;

[0046] The concentration of the accelerator is 1.0%, specifically cyclopropyl phenyl sulfide;

[0047] The concentration of the stabilizer is 1.5%, specifically 3-mercapto-N-methyl-propionamide;

[0048] The concentration of the wetting agent is 1.0%, specifically 3,5-dihydroxybenzohydrazide;

[0049] The concentration of the complexing agent is 1.5%, and its structural formula is:

[0050] ;

[0051] The remainder is distilled water.

[0052] Example 2

[0053] Weigh the reducing agent, accelerator, stabilizer, wetting agent, complexing agent and distilled water in sequence according to the following mass concentration formula, add them to the reaction kettle, and stir and mix at room temperature for 30 minutes to obtain the electroless copper plating additive of this example, and store it sealed for later use.

[0054] The concentration of the reducing agent is 1.5%, specifically 4,6-dichlorosalicylaldehyde;

[0055] The concentration of the accelerator is 1.0%, specifically cyclobutyl phenyl sulfide;

[0056] The concentration of the stabilizer is 1.5%, specifically 3-mercapto-N-nonylpropanamide;

[0057] The concentration of the wetting agent is 1.0%, specifically 3,4-diaminobenzohydrazide;

[0058] The concentration of the complexing agent is 1.5%, and its structural formula is:

[0059] ;

[0060] The remainder is distilled water.

[0061] Example 3

[0062] Weigh the reducing agent, accelerator, stabilizer, wetting agent, complexing agent and distilled water in sequence according to the following mass concentration formula, add them to the reaction kettle, and stir and mix at room temperature for 30 minutes to obtain the electroless copper plating additive of this example, and store it sealed for later use.

[0063] The concentration of the reducing agent is 1.5%, specifically 4,5-dichlorosalicylaldehyde;

[0064] The concentration of the accelerator is 1.0%, specifically 2-nitrodiphenyl sulfide;

[0065] The concentration of the stabilizer is 1.5%, specifically 6-mercaptopyridine-3-sulfonamide;

[0066] The concentration of the wetting agent is 1.0%, specifically 3-amino-4-hydroxybenzohydrazide;

[0067] The concentration of the complexing agent is 1.5%, and its structural formula is:

[0068] ;

[0069] The remainder is distilled water.

[0070] Example 4

[0071] Weigh the reducing agent, accelerator, stabilizer, wetting agent, complexing agent and distilled water in sequence according to the following mass concentration formula, add them to the reaction kettle, and stir and mix at room temperature for 30 minutes to obtain the electroless copper plating additive of this example, and store it sealed for later use.

[0072] The concentration of the reducing agent is 0.5%, specifically 3,5-dichlorosalicylaldehyde;

[0073] The concentration of the accelerator is 0.2%, specifically cyclopropyl phenyl sulfide;

[0074] The concentration of the stabilizer is 0.5%, specifically 3-mercapto-N-methyl-propionamide;

[0075] The concentration of the wetting agent is 0.2%, specifically 3,5-dihydroxybenzohydrazide;

[0076] The concentration of the complexing agent is 0.5%, and its structural formula is:

[0077] ;

[0078] The balance is distilled water.

[0079] Example 5

[0080] Weigh the reducing agent, accelerator, stabilizer, wetting agent, complexing agent and distilled water in sequence according to the following mass concentration formula, add them to the reaction kettle, and stir and mix at room temperature for 30 minutes to obtain the electroless copper plating additive of this example, and store it sealed for later use.

[0081] The concentration of the reducing agent is 3.0%, specifically 3,5-dichlorosalicylaldehyde;

[0082] The concentration of the accelerator is 2.0%, specifically cyclopropyl phenyl sulfide;

[0083] The concentration of the stabilizer is 3.0%, specifically 3-mercapto-N-methyl-propionamide;

[0084] The concentration of the wetting agent is 2.0%, specifically 3,5-dihydroxybenzohydrazide;

[0085] The concentration of the complexing agent is 3.0%, and its structural formula is:

[0086] ;

[0087] The balance is distilled water.

[0088] In the process of exploring the copper plating effect of electroless copper plating additives with different formulas in the present invention, electroless copper plating additives of the following comparative examples were also prepared.

[0089] Comparative Example 1

[0090] The electroless copper plating additive of Comparative Example 1 is different from that of Example 1 only in that: the component does not contain a reducing agent.

[0091] Comparative Example 2

[0092] The electroless copper plating additive of Comparative Example 2 is different from that of Example 1 only in that: the component does not contain an accelerator.

[0093] Comparative Example 3

[0094] The electroless copper plating additive of Comparative Example 3 is different from that of Example 1 only in that: the component does not contain a stabilizer.

[0095] Comparative Example 4

[0096] The electroless copper plating additive of Comparative Example 4 is different from that of Example 1 only in that: the component does not contain a wetting agent.

[0097] Comparative Example 5

[0098] The electroless copper plating additive of Comparative Example 5 is different from that of Example 1 only in that: the component does not contain a complexing agent.

[0099] Comparative Example 6

[0100] The electroless copper plating additive of Comparative Example 6 is different from that of Example 1 only in that: the concentration of the reducing agent in the component is 0.2%.

[0101] Comparative Example 7

[0102] The electroless copper plating additive of Comparative Example 7 is different from that of Example 1 only in that: the concentration of the accelerator in the component is 0.1%.

[0103] Comparative Example 8

[0104] The electroless copper plating additive of Comparative Example 8 is different from that of Example 1 only in that: the concentration of the stabilizer in the component is 0.2%.

[0105] Comparative Example 9

[0106] The electroless copper plating additive of Comparative Example 9 is different from that of Example 1 only in that: the concentration of the wetting agent in the component is 0.1%.

[0107] Comparative Example 10

[0108] The electroless copper plating additive of Comparative Example 10 is different from that of Example 1 only in that: the concentration of the complexing agent in the component is 0.2%.

[0109] Comparative Example 11

[0110] The electroless copper plating additive of Comparative Example 11 is the electroless copper plating additive disclosed in the prior art (Chinese Patent Application CN 110499501 A), and its specific components include: 3 g / L of formaldehyde; 80 g / L of sodium potassium tartrate; 5 mg / L of 1,10-phenanthroline; 5 mg / L of cytosine; 50 mg / L of water-soluble polyethylene glycol (molecular weight of 1000), and the balance is distilled water.

[0111] The electroless copper plating additive of the above-mentioned examples or comparative examples is used for electroless copper plating of an IC carrier (test sample). The electroless copper plating process is as follows: S1 Water washing → S2 Degreasing → S3 Water washing → S4 Micro-etching → S5 Water washing → S6 Pre-impregnation → S7 Activation → S8 Electroless copper plating → S9 Water washing → S10 Drying. Specifically as follows.

[0112] In the S1 water washing process, the IC carrier is washed with DI water to clean the surface impurities. The process parameters of the water washing process are: in the spray mode, the length of the water washing tank is 2.0 m, the temperature of the tank solution is 25 ± 5°C; the linear speed is 3.0 ± 0.5 m / min, and the pressure is 1.5 ± 0.5 kg / cm 2 ;

[0113] In the S2 degreasing process, the IC carrier after the S1 water washing process is soaked in an alkaline solution for degreasing. The process parameters of the degreasing process are: in the soaking mode, the solution in the degreasing tank contains 1% sodium hydroxide by mass fraction, and the balance is DI water; the soaking time of the alkaline solution is 3 ± 1 min, and the temperature of the alkaline solution is 50 ± 5°C;

[0114] In the S3 water washing process, the IC carrier after the S2 degreasing process is washed with DI water to clean the surface impurities. The process parameters of the water washing process are: in the spray mode, the length of the water washing tank is 2.0 m, the temperature of the tank solution is 25 ± 5°C; the linear speed is 3.0 ± 0.5 m / min, and the pressure is 1.5 ± 0.5 kg / cm 2 ;

[0115] In the S4 micro-etching process, the surface of the IC carrier after the S3 water washing process is micro-etched with an etching solution to improve the adhesion of the copper surface. The process parameters of the micro-etching process are: in the spray mode, the solution in the micro-etching tank contains the micro-etching solution BTH-2011R of Shenzhen Banming Technology Co., Ltd., with a content of 5 wt%, and the balance is DI water; the length of the micro-etching tank is 2.0 m, the temperature of the tank solution is 25 ± 5°C; the linear speed is 3.0 ± 0.5 m / min, and the pressure is 1.5 ± 0.5 kg / cm 2 ;

[0116] The S5 water washing process is to wash the IC carrier board that has undergone the S4 micro-etching process with DI water to clean the surface impurities. The process parameters of the water washing process are as follows: The spraying method is adopted, the length of the water washing tank is 2.0 m, the temperature of the tank solution is 25 ± 5 °C; the linear speed is 3.0 ± 0.5 m / min, and the pressure is 1.5 ± 0.5 kg / cm 2 ;

[0117] The S6 pre-impregnation process is to treat the IC carrier board that has undergone the S5 water washing process with a pre-impregnation solution. The process parameters of the pre-impregnation process are as follows: The soaking method is adopted, the pre-impregnation tank solution contains 3% hydrochloric acid by mass fraction, and the balance is DI water; the soaking time is 3 ± 1 min, and the temperature of the pre-impregnation tank solution is 25 ± 5 °C;

[0118] The S7 activation process is to treat the IC carrier board that has undergone the S6 pre-impregnation process with an activation solution. The process parameters of the activation process are as follows: The soaking method is adopted, the activation tank solution contains 3% hydrochloric acid and 5% palladium chloride by mass fraction, and the balance is DI water; the soaking time is 3 ± 1 min, and the temperature of the activation tank solution is 25 ± 5 °C;

[0119] The S8 electroless copper plating process is to treat the IC carrier board that has undergone the S7 activation process with an electroless copper plating solution. The process parameters of the electroless copper plating process are as follows: The soaking method is adopted, the electroless copper plating solution in the electroless copper plating tank contains 5% copper sulfate and 5% electroless copper plating additive of the embodiment or comparative example of the present invention by mass fraction, and the balance is DI water; the soaking time is 40.0 min, and the temperature of the electroless copper plating solution is 50 ± 0.2 °C;

[0120] The S9 water washing process is to wash the IC carrier board that has undergone the S8 electroless copper plating process with DI water to clean the surface impurities. The process parameters of the water washing process are as follows: The spraying method is adopted, the length of the water washing tank is 2.0 m, the temperature of the tank solution is 25 ± 5 °C; the linear speed is 3.0 ± 0.5 m / min, and the pressure is 1.5 ± 0.5 kg / cm 2 ;

[0121] The S10 drying process is to dry the IC carrier board after the S9 water washing process. The process parameters of drying are as follows: The temperature is 70 ± 5 °C, the length of the drying section is 2.0 m, and the linear speed is 4.0 ± 0.3 m / min.

[0122] The IC carrier boards (test samples) after the electroless copper plating treatment of the above embodiments or comparative examples are subjected to the following performance tests. The specific test items and methods are as follows.

[0123] Stability of plating solution: Take the electroless copper plating solution in the electroless copper plating tank of each embodiment or comparative example with a beaker and observe the copper deposition situation after placing it for 48 h.

[0124] Uniformity: Use a roughness measuring instrument to test the roughness value Ra of the coating. The lower the Ra value, the more uniform the coating surface. At the same time, observe whether small copper crystals appear on the copper layer after electroless copper plating.

[0125] Adhesion: Keep the electroless copper-plated IC carrier plate at 260 °C for 1 h, take it out and quickly cool it in cold water; repeat 10 times. If the coating does not peel off, it is qualified.

[0126] Deposition rate: Test by the weight gain method. Specifically, take an ABF (Ajinomoto build-up film) substrate plate with dimensions of 50 cm in length × 50 cm in width × 2 cm in thickness and place it in the electroless copper plating bath for 1 h of copper plating. Weigh the mass before and after electroless copper plating. The deposition rate (μm / h) = weight gain of electroless copper plating (g) × 11.2 × 60 / total deposition area (dm 2 ) × electroless copper plating time (h).

[0127] Degree of overplating: Take an ABS+PC (linear carbonate polyester) composite substrate plate with dimensions of 50 cm in length × 50 cm in width × 2 cm in thickness. Among them, the material in the middle of the ABS+PC substrate plate is ABS (250 mm in length × 25 mm in width), and the surrounding material is PC; after degreasing and etching the ABS+PC plate, activate the substrate with an ionic palladium activation solution, so that only the ABS area is activated. During the electroless copper plating process, a copper coating can only be formed in the ABS area; after 1 h of electroless copper plating, use a dimension measuring instrument to measure the dimensions of the copper coating in the length and width directions. Take the ratio of the difference between this dimension and the initial dimension of the ABS area to 2 as the degree of overplating. Measure 10 random positions at equal intervals along the length and width directions, and take the average value of all measured values as the standard for evaluating the degree of overplating.

[0128] The performance test results of the IC carrier plates in Examples 1-5 and Comparative Examples 1-11 are shown in Table 1.

[0129] Table 1 Performance test results

[0130]

[0131] From the test results of Examples 1-5 in Table 1, it can be seen that the electroless copper plating solution obtained by using the electroless copper plating additive of the present invention has good stability and no copper precipitation after being placed for 48 h; the uniformity and adhesion of the coating obtained after electroless copper plating are good, the Ra value is between 0.22 and 0.25, and there are no small particle crystals on the coating; at the same time, the plating solution has a relatively fast deposition rate, about 13.5 μm / h, and the degree of overplating is only 1.5-1.7 μm, which can be used in the electroless copper plating production process of IC carrier plates.

[0132] The differences between Comparative Examples 1-5 and Example 1 are that the electroless copper plating additives of the present invention lack a reducing agent, an accelerator, a stabilizer, a wetting agent, and a complexing agent single component respectively. The test results show that the electroless copper plating effect of the IC substrate is related to the functions of each additive component. The lack of any component will affect the stability, uniformity, adhesion, deposition rate, and overflow plating degree of electroless copper plating. The role of the reducing agent is to reduce copper ions in the formed complex to metallic copper. When the reducing agent is missing in the component, no coating can be obtained; the accelerator, stabilizer, wetting agent, and complexing agent play corresponding functions. The complexing agent used in the present invention is a macrocyclic compound composed of methylene-bridged phenol units. It has rich hydrocarbon reaction sites on its structural formula, and there is a possibility of functionalization on the upper edge, lower edge, and sulfur atoms of the bridge chain, and it can exhibit excellent complexing performance with metal ions. At the same time, this complexing agent has the effects of accelerating electroless copper plating and improving the stability of the electroless copper plating solution. When the complexing agent component is missing, the electroless copper plating effect decreases more significantly.

[0133] The differences between Comparative Examples 6-10 and Example 1 are that the reducing agent, accelerator, stabilizer, wetting agent, and complexing agent in the electroless copper plating additives of the present invention are respectively lower than the lower limit value of the mass concentration defined by the present invention. The test results show that the decrease in the mass concentration of each component will cause the electroless copper plating effect to decline and cannot meet the requirements of electroless copper plating of the IC substrate. Therefore, the concentration of each component must be controlled within the concentration range of the present invention.

[0134] Comparative Example 11 uses an electroless copper plating solution containing an electroless copper plating additive of the prior art for comparison. The test results show that the electroless copper plating solution using the electroless copper plating additive of the present invention has better stability, uniformity, adhesion, deposition rate, and overflow plating degree of electroless copper plating.

[0135] The slicing effect of the IC substrate after electroless copper plating in Example 1 is as Figure 2 shown; the slicing effect of the IC substrate after electroless copper plating in Comparative Example 11 is as Figure 3 shown.

[0136] It can be seen from this that the electroless copper plating additive containing effective components such as a reducing agent, an accelerator, a stabilizer, a wetting agent, and a complexing agent of the present invention can effectively improve the stability of the electroless copper plating solution, and the uniformity, adhesion, and deposition rate of the coating are good. The deposition rate and the overflow plating degree can meet the production of electroless copper plating of the IC substrate.

[0137] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. An additive for chemical copper plating, characterized in that: It is composed of the following components in mass fractions: Complexing agent 0.5-3.0%, Reducing agent 0.5-3.0%, Accelerator 0.2-2.0%, Stabilizer 0.5-3.0%, Wetting agent 0.2-2.0%, The balance is water; The complexing agent structural formula is as follows: Where n is 4 or 6 or 8; The reducing agent is selected from at least one of 3,5-dichlorosalicylaldehyde, 4,6-dichlorosalicylaldehyde and 4,5-dichlorosalicylaldehyde; The accelerator is selected from at least one of cyclopropyl benzene sulfide, cyclobutyl benzene sulfide, and 2-nitrodiphenyl sulfide; The stabilizer is selected from at least one of 3-mercapto-N-methyl-propionamide, 3-mercapto-N-nonylpropionamide, and 6-mercaptopyridine-3-sulfonamide; The wetting agent is selected from at least one of 3,5-dihydroxybenzohydrazide, 3,4-diaminobenzohydrazide and 3-amino-4-hydroxybenzohydrazide.

2. The chemical copper plating additive according to claim 1, characterized in that: The preparation method of the complexing agent is as follows: Based on 100 parts by weight, 4-6 parts of catechol, 0.8-1.2 parts of potassium carbonate, 0.4-0.6 parts of potassium iodide, 4-6 parts of 2-chloroethoxyethanol and 25-35 parts of acetonitrile are added into a reaction container, and heated at 65-70° C. for 1-2 hours; Then add 4-6 parts of 4-dimethylaminopyridine, 0.8-1.2 parts of triethylamine, 1.5-2.5 parts of 1,2-dichloroethylene, and 0.8-1.2 parts of p-toluenesulfonyl chloride, and heat at 75-80° C. for 3-4 hours; Add 0.4-0.6 parts of ethanol and 0.8-1.2 parts of toluene as solvents, add 4-6 parts of alkane dithiol and the balance of water, heat at 85-90° C. for 5-6 hours, cool to room temperature, and extract with dichloromethane and water to obtain a complexing agent; The alkane dithiol is selected from 1,4-butanedithiol, 1,6-hexanedithiol or 1,8-octanedithiol.

3. A chemical copper plating solution, characterized in that Contains the chemical copper plating additive as claimed in claim 1 or 2.

4. The chemical copper plating solution according to claim 3, characterized in that: The invention is composed of the following components in mass fractions: 4-6% copper sulfate, 4-6% chemical copper plating additive, and the balance being water.

5. A method for chemical copper plating of an IC substrate, characterized in that: The method comprises a chemical copper plating step of immersing the IC carrier board in the chemical copper plating solution as claimed in claim 3 or 4 at 50±0.2° C. for 35-45 minutes.

6. The IC substrate chemical copper plating method according to claim 5, characterized in that: The chemical copper plating process also includes an activation process before the process; the activation process is specifically: immersing the IC substrate in an activation tank solution at 25±5°C for 3±1min; the activation tank solution contains 3% by mass hydrochloric acid and 5% by mass palladium chloride, and the remainder is DI water.

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