PCB Inkjet Printing Pretreatment Agent, Its Preparation Method and PCB Inkjet Printing Method

Abstract

The present invention discloses a pretreatment agent for PCB inkjet printing, a preparation method thereof, and a PCB inkjet printing method, which relate to the technical field of printed circuit board production. The pretreatment agent for PCB inkjet printing is composed of the following components in mass concentration: an anti-diffusion agent 0.1 - 0.5%, a wetting agent 0.1 - 0.5%, a leveling agent 0.2 - 1.0%, a dispersant 0.5 - 2.5%, a co-solvent 0.1 - 3.0%, and the balance is water. The pretreatment agent for PCB inkjet printing of the present invention can be used in the surface treatment process of the fine PCB pattern inkjet printing process, and can form a uniform organic layer on the copper surface and the substrate surface of the PCB. This organic layer can not only effectively reduce the surface tension of the copper surface and the substrate surface, prevent the printed ink from diffusing on the PCB surface, but also promote the uniform arrangement of the ink, which is beneficial to forming a stable and neat linear ink, and improving the product yield of the fine line inkjet printing process.

Description

Technical Field

[0001] The present invention relates to the technical field of printed circuit board production, and in particular to a pretreatment agent for PCB inkjet printing, a preparation method thereof, and a PCB inkjet printing method. Background Art

[0002] Since the 21st century, with the rise of emerging technologies such as smart phones and artificial intelligence, printed circuit boards (PCBs) have entered a new stage of miniaturization and thinning. From a technical perspective, the circuit design of PCBs has been continuously refined, the line width and line pitch have been continuously reduced, and some enterprises have successfully achieved the production process of 30μm fine lines, improving the overall performance of the circuit. From a market perspective, the demand in fields such as smart phones, automotive electronics, medical devices, and industrial control has continued to grow, and the demand for fine lines on PCBs has increased greatly. Line refinement is one of the directions of future technological development.

[0003] PCB inkjet printing technology is based on pre-designed PCB graphic data. The control system precisely manipulates the movement of the print head on the PCB, as well as the jetting timing and jetting amount of the ink, so that the ink is deposited on the substrate according to a predetermined pattern to form various graphics required for PCBs, such as conductive lines, solder mask layers, character markings, etc. In addition, in the solder mask process, the printing device can precisely spray the ink on the surface of the PCB to cover the areas that do not need to be soldered, preventing problems such as short circuits during the soldering process and improving the soldering quality and the reliability of the PCB. Compared with traditional PCB manufacturing processes, such as photolithography and screen printing, inkjet printing technology does not require complex processes such as plate making, developing, and etching. It can directly spray the ink onto the substrate to form the required graphics, greatly shortening the production cycle and improving production efficiency. Moreover, PCB inkjet printing technology can achieve micron-level printing accuracy, with a positioning accuracy of up to ±35μm and a repeat accuracy of up to ±5μm, and has a relatively high printing resolution, which can meet the production requirements of high-density PCB lines and fine graphics. With the continuous progress of technology, inkjet printing technology will develop towards higher resolution and higher accuracy to meet the future requirements of PCBs for higher density and smaller size, and has good development prospects.

[0004] At present, good research progress has been made in the research on inkjet printing ink anti-diffusion agents. Patent CN118290987A discloses a PCB inkjet printing anti-diffusion agent, which contains components such as oil repellent 1, oil repellent 2, wetting agent, stabilizer, co-solvent, etc. It can form an organic layer on the copper surface and the substrate surface of the circuit board, strengthening the bonding force between the copper surface and the substrate surface and the ink. Among them, the contact angle between the copper surface and the solder mask ink is greater than 90°, and the contact angle between the substrate surface and the solder mask ink is greater than 80°, which can effectively slow down the diffusion rate of the printed ink on the copper surface and the substrate surface and prevent the ink from spreading around the PCB surface before curing.

[0005] Inkjet printing technology is relatively mature in the printing of PCB character identification, but less applied in the printing of PCB circuits and solder masks. The existing technology uses a treatment process of "ultra-roughening + anti-diffusion agent", which can effectively solve the problems of inkjet ink diffusion and adhesion, and helps to promote the industrial application of inkjet printing technology. At present, many PCB enterprises are constantly carrying out inkjet printing tests. Although they have not been officially put into production, good results have been achieved. The existing technology can meet the inkjet printing of ordinary PCBs, but when printing fine circuits, the ink will diffuse, resulting in problems such as crooked circuits, incomplete printing, and overlapping circuits, which increases the defective rate of the products of this process, increases the rework cost or causes scrapping. Therefore, a pretreatment agent for inkjet printing before PCB is needed to meet the production of fine circuit inkjet printing. Summary of the Invention

[0006] To solve the above technical problems, the object of the present invention is achieved through the following technical solutions.

[0007] Provide a pretreatment agent for PCB inkjet printing, which is composed of the following components in mass concentration:

[0008] Anti-diffusion agent 0.1 - 0.5%,

[0009] Wetting agent 0.1 - 0.5%,

[0010] Homogenizer 0.2 - 1.0%,

[0011] Dispersant 0.5 - 2.5%,

[0012] Co-solvent 0.1 - 3.0%,

[0013] The balance is water;

[0014] The anti-diffusion agent is a fluorobenzenethiol compound, the wetting agent is a polyethylene glycol acrylate compound, the homogenizer is a carboxylic acid phenyl ester compound, the dispersant is a carboxybenzo crown ether compound, and the co-solvent is a pinacol ester compound.

[0015] Preferably, the anti-diffusion agent is selected from at least one of 2,4-difluorobenzenethiol (CAS No.: 1996-44-7), 3,4-difluorobenzenethiol (CAS No.: 60811-24-7), and 3,5-difluorobenzenethiol (CAS No.: 99389-26-1).

[0016] Preferably, the wetting agent is selected from at least one of methoxypolyethylene glycol (350) acrylate (CAS No.: 32171-39-4), polyethylene glycol (400) methacrylate (CAS No.: 9051-31-4), and polyethylene glycol (400) monoacrylate (CAS No.: 9051-31-4); the "350" and "400" in the parentheses refer to the average molecular weight of the polyethylene glycol chain segment.

[0017] Preferably, the homogenizing agent is selected from at least one of diphenyl phenylphosphonate (CAS No.: 3049-24-9), diphenyl malonate (CAS No.: 1969-44-4), and benzyl phenyl glycolate (CAS No.: 30379-58-9).

[0018] Preferably, the dispersing agent is selected from at least one of 4'-carboxybenzo-15-crown-5-ether (CAS No.: 56683-55-7) and 4'-carboxybenzo-18-crown-6-ether (CAS No.: 60835-75-8).

[0019] Preferably, the cosolvent is selected from at least one of 6-quinolineboronic acid pinacol ester (CAS No.: 406463-06-7) and 4-benzylphenylboronic acid pinacol ester (CAS No.: 911708-01-5).

[0020] The preparation method of the above PCB inkjet printing pretreatment agent is as follows: put the anti-diffusion agent, wetting agent, homogenizing agent, dispersing agent, cosolvent and water into a reaction vessel, mix them evenly at 55-65 °C, and obtain the PCB inkjet printing pretreatment agent after cooling to room temperature.

[0021] Preferably, the preparation method of the above PCB inkjet printing pretreatment agent is as follows: put the anti-diffusion agent, wetting agent, homogenizing agent, dispersing agent, cosolvent and water into a reaction vessel, mix them at 55-65 °C for 20-60 min, and obtain the PCB inkjet printing pretreatment agent after cooling to room temperature.

[0022] The present invention also provides a PCB inkjet printing method, which includes the following steps:

[0023] Surface treatment: Immerse the PCB in the above PCB inkjet printing pretreatment agent for 1.5-3 min.

[0024] Inkjet printing: Perform inkjet and curing on the PCB after surface treatment.

[0025] Furthermore, before the surface treatment, it also includes super roughening treatment: performing super roughening etching on the PCB.

[0026] Preferably, the amount of super roughening etching is 0.8-1.0 μm.

[0027] The pretreatment agent for PCB inkjet printing of the present invention can be used in the surface treatment process of the fine PCB pattern inkjet printing process. The pretreatment agent contains effective components such as an anti-diffusion agent, a wetting agent, a leveling agent, a dispersant, and a co-solvent, and can form a uniform organic layer on the copper surface and the substrate surface of the PCB. This organic layer can not only effectively reduce the surface tension of the copper surface and the substrate surface, prevent the printed ink from spreading on the PCB surface, but also promote the uniform arrangement of the ink, which is beneficial to forming a stable and neat linear ink, and improving the product yield of the fine line inkjet printing process.

[0028] In the pretreatment agent for PCB inkjet printing of the present invention, the anti-diffusion agent mainly acts on the surface of the PCB board to reduce the surface tension of the copper surface and the substrate surface, achieving the effect of preventing ink diffusion. The wetting agent is a type of surfactant containing both hydrophilic and lipophilic functional groups, which can reduce the surface tension of the PCB surface and also enable the effective components in the pretreatment agent to fully contact the PCB surface. The leveling agent can, on the one hand, accelerate the penetration and diffusion of the effective components in the pretreatment agent, and on the other hand, has a "lubricating" effect, enhancing the fluidity of the effective components in the pretreatment agent and improving the uniformity of wetting. The dispersant can improve the dispersibility, fluidity, and uniformity of each component in the pretreatment agent, making the organic layer formed by the pretreatment agent on the PCB board surface more flat. The co-solvent is used to dissolve the components that are poorly soluble in water, forming a relatively stable solution system. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0030] Figure 1 Copper surface ink line for Example 1;

[0031] Figure 2 Substrate surface ink line for Example 1;

[0032] Figure 3 Copper surface ink line for Comparative Example 1;

[0033] Figure 4 Substrate surface ink line for Comparative Example 1. Detailed Description of the Invention

[0034] The technical solution 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 belong to the scope of protection of the present invention.

[0035] Example 1

[0036] Weigh the anti-diffusion agent, wetting agent, leveling agent, dispersant, co-solvent and the remaining water in sequence according to the following formula (mass concentration), add them to the reaction kettle, stir and mix at 60 °C for 30 minutes, and then cool to room temperature to obtain the pretreatment agent for PCB inkjet printing in this example.

[0037] The content of the anti-diffusion agent is 0.1%, specifically: 2,4-difluorobenzenethiol;

[0038] The content of the wetting agent is 0.3%, specifically: methoxypolyethylene glycol (350) acrylate;

[0039] The content of the leveling agent is 0.5%, specifically diphenyl phenylphosphonate;

[0040] The content of the dispersant is 1.5%, specifically: 4'-carboxybenzo-15-crown-5-ether;

[0041] The content of the co-solvent is 1.5%, specifically: 6-quinolineboronic acid pinacol ester;

[0042] The remaining is water.

[0043] Example 2

[0044] Weigh the anti-diffusion agent, wetting agent, leveling agent, dispersant, co-solvent and the remaining water in sequence according to the following formula (mass concentration), add them to the reaction kettle, stir and mix at 60 °C for 30 minutes, and then cool to room temperature to obtain the pretreatment agent for PCB inkjet printing in this example.

[0045] The content of the anti-diffusion agent is 0.1%, specifically: 3,4-difluorobenzenethiol;

[0046] The content of the wetting agent is 0.3%, specifically: polyethylene glycol (400) methacrylate;

[0047] The content of the leveling agent is 0.5%, specifically diphenyl malonate;

[0048] The content of the dispersant is 1.5%, specifically: 4'-carboxybenzo-18-crown-6-ether;

[0049] The content of the co-solvent is 1.5%, specifically: 4-benzylphenylboronic acid pinacol ester;

[0050] The balance is water.

[0051] Example 3

[0052] Weigh the anti-diffusion agent, wetting agent, leveling agent, dispersant, co-solvent and the balance of water in sequence according to the following formula (mass concentration), add them into the reaction kettle, stir and mix at 60 °C for 30 minutes, and then cool to room temperature to obtain the pre-treatment agent for PCB inkjet printing of this example.

[0053] The content of the anti-diffusion agent is 0.1%, specifically: 3,5-difluorobenzenethiol;

[0054] The content of the wetting agent is 0.3%, specifically: polyethylene glycol (400) monoacrylate;

[0055] The content of the leveling agent is 0.5%, specifically: benzyl glycolate;

[0056] The content of the dispersant is 1.5%, specifically: 4'-carboxybenzo-15-crown-5-ether;

[0057] The content of the co-solvent is 1.5%, specifically: 4-benzylphenylboronic acid pinacol ester;

[0058] The balance is water.

[0059] Example 4

[0060] Weigh the anti-diffusion agent, wetting agent, leveling agent, dispersant, co-solvent and the balance of water in sequence according to the following formula (mass concentration), add them into the reaction kettle, stir and mix at 60 °C for 30 minutes, and then cool to room temperature to obtain the pre-treatment agent for PCB inkjet printing of this example.

[0061] The content of the anti-diffusion agent is 0.1%, specifically: 2,4-difluorobenzenethiol;

[0062] The content of the wetting agent is 0.3%, specifically: polyethylene glycol (400) methacrylate;

[0063] The content of the leveling agent is 0.5%, specifically: benzyl glycolate;

[0064] The content of the dispersant is 1.5%, specifically: 4'-carboxybenzo-18-crown-6-ether;

[0065] The content of the co-solvent is 1.5%, specifically: 4-benzylphenylboronic acid pinacol ester;

[0066] The balance is water.

[0067] Example 5

[0068] According to the following formula (mass concentration), successively weigh the anti-diffusion agent, wetting agent, leveling agent, dispersant, co-solvent and the balance of water and add them into the reaction kettle. After stirring and mixing at 60 °C for 30 minutes, cool to room temperature to obtain the PCB inkjet printing pretreatment agent of this example.

[0069] The content of the anti-diffusion agent is 0.3%, specifically: 3,5-difluorobenzenethiol;

[0070] The content of the wetting agent is 0.3%, specifically: methoxypolyethylene glycol (350) acrylate;

[0071] The content of the leveling agent is 0.5%, specifically diphenyl phenylphosphonate;

[0072] The content of the dispersant is 1.5%, specifically diphenyl malonate;

[0073] The content of the co-solvent is 1.5%, specifically 6-quinolineboronic acid pinacol ester;

[0074] The balance is water.

[0075] Example 6

[0076] According to the following formula (mass concentration), successively weigh the anti-diffusion agent, wetting agent, leveling agent, dispersant, co-solvent and the balance of water and add them into the reaction kettle. After stirring and mixing at 55 °C for 60 minutes, cool to room temperature to obtain the PCB inkjet printing pretreatment agent of this example.

[0077] The content of the anti-diffusion agent is 0.1%, specifically: 2,4-difluorobenzenethiol;

[0078] The content of the wetting agent is 0.1%, specifically: methoxypolyethylene glycol (350) acrylate;

[0079] The content of the leveling agent is 0.2%, specifically diphenyl phenylphosphonate;

[0080] The content of the dispersant is 0.5%, specifically 4'-carboxybenzo-15-crown-5-ether;

[0081] The content of the co-solvent is 0.1%, specifically 6-quinolineboronic acid pinacol ester;

[0082] The balance is water.

[0083] Example 7

[0084] According to the following formula (mass concentration), successively weigh the anti-diffusion agent, wetting agent, leveling agent, dispersant, co-solvent and the balance of water and add them into the reaction kettle. After stirring and mixing at 65 °C for 25 minutes, cool to room temperature to obtain the PCB inkjet printing pretreatment agent of this example.

[0085] The content of the anti-diffusion agent is 0.5%, specifically: 2,4-difluorobenzenethiol;

[0086] The content of the wetting agent is 0.5%, specifically: methoxypolyethylene glycol (350) acrylate;

[0087] The content of the homogenizing agent is 1.0%, specifically diphenyl phenylphosphonate;

[0088] The content of the dispersing agent is 2.5%, specifically 4'-carboxybenzo-15-crown-5-ether;

[0089] The content of the cosolvent is 3%, specifically 6-quinolineboronic acid pinacol ester;

[0090] The balance is water.

[0091] In the process of exploring the effects of PCB inkjet printing pretreatment agents with different component systems, the present invention also prepared PCB inkjet printing pretreatment agents for the following comparative examples.

[0092] Comparative Example 1

[0093] The PCB inkjet printing pretreatment agent of Comparative Example 1 is different from that of Example 1 only in that the component does not contain an anti-diffusion agent.

[0094] Comparative Example 2

[0095] The PCB inkjet printing pretreatment agent of Comparative Example 2 is different from that of Example 1 only in that the component does not contain a wetting agent.

[0096] Comparative Example 3

[0097] The PCB inkjet printing pretreatment agent of Comparative Example 3 is different from that of Example 1 only in that the component does not contain a homogenizing agent.

[0098] Comparative Example 4

[0099] The PCB inkjet printing pretreatment agent of Comparative Example 4 is different from that of Example 1 only in that the component does not contain a dispersing agent.

[0100] Comparative Example 5

[0101] The PCB inkjet printing pretreatment agent of Comparative Example 5 is different from that of Example 1 only in that the component does not contain a cosolvent.

[0102] Comparative Example 6

[0103] The PCB inkjet printing pretreatment agent of Comparative Example 6 is different from that of Example 1 only in that the concentration of the anti-diffusion agent in the component is 1.0%.

[0104] Comparative Example 7

[0105] The pretreatment agent for PCB inkjet printing of Comparative Example 7 is different from that of Example 1 only in that the concentration of the wetting agent in the components is 1.0%.

[0106] Comparative Example 8

[0107] The pretreatment agent for PCB inkjet printing of Comparative Example 8 is different from that of Example 1 only in that the concentration of the homogenizer in the components is 2.0%.

[0108] Comparative Example 9

[0109] The pretreatment agent for PCB inkjet printing of Comparative Example 9 is different from that of Example 1 only in that the concentration of the dispersant in the components is 5.0%.

[0110] Comparative Example 10

[0111] The pretreatment agent for PCB inkjet printing of Comparative Example 10 is different from that of Example 1 only in that the concentration of the cosolvent in the components is 6.0%.

[0112] Comparative Example 11

[0113] The pretreatment agent for PCB inkjet printing of Comparative Example 11 is different from that of Example 1 only in that the anti-diffusion agent component 2,4-difluorobenzenethiol is replaced with sodium benzenethiolate (CAS No.: 930-69-8).

[0114] Comparative Example 12

[0115] The pretreatment agent for PCB inkjet printing of Comparative Example 12 is different from that of Example 1 only in that the wetting agent component methoxypolyethylene glycol (350) acrylate is replaced with triethylene glycol dimethacrylate (CAS No.: 109-16-0).

[0116] Comparative Example 13

[0117] The pretreatment agent for PCB inkjet printing of Comparative Example 13 is different from that of Example 1 only in that the homogenizer component diphenyl phenylphosphonate is replaced with methyl pyrrole-2-carboxylate (CAS No.: 1193-62-0).

[0118] Comparative Example 14

[0119] The pretreatment agent for PCB inkjet printing of Comparative Example 14 is different from that of Example 1 only in that the dispersant component 4'-carboxybenzo-15-crown-5-ether is replaced with 15-crown-5 (CAS No.: 33100-27-5).

[0120] Comparative Example 15

[0121] Comparative Example 15 uses a PCB inkjet printing anti-diffusion agent of the prior art (Chinese Patent Application CN118290987A). Specifically, its components include:

[0122] The content of oil-repellent 1 is 0.1%, specifically: dicyclohexano-18-crown-6;

[0123] The content of oil-repellent 2 is 0.3%, specifically: 5-amino-2-naphthalenesulfonic acid;

[0124] The content of wetting agent is 0.5%, specifically 3-sulfopropyltetradecyldimethylbetaine;

[0125] The content of stabilizer is 1.5%, specifically methyl 3,4-diaminobenzoate;

[0126] The content of co-solvent is 1.5%, specifically 1-amino-4-piperidinol;

[0127] The balance is water.

[0128] The PCB inkjet printing pretreatment agent or PCB inkjet printing anti-diffusion agent of the above Examples 1-7 and Comparative Examples 1-15 are respectively used in the production of fine PCB pattern inkjet printing. The process includes the following steps: S1 Water washing; S2 Degreasing; S3 Water washing; S4 Super roughening; S5 Water washing; S6 Hydrochloric acid washing; S7 Water washing; S8 Surface treatment; S9 Water washing; S10 Drying; S11 Inkjet printing.

[0129] The specific process flow is as follows:

[0130] In the S1 water washing stage, the printed circuit board to be inkjet printed is put into tap water for water washing. The process parameters of the water washing stage are: This stage is immersion type, the water washing temperature is 25±1°C, the length of the water washing stage is 1.0 m, and the line speed is 2.0±0.2 m / min;

[0131] In the S2 degreasing stage, the printed circuit board passing through the S1 water washing stage is cleaned to remove surface impurities. The process parameters of the degreasing stage are: This stage is spray type, the sulfuric acid concentration is 0.5%, and the balance is tap water; the degreasing temperature is 25±1°C, the length of the degreasing stage is 2.0 m; the line speed is 2.0±0.2 m / min, and the pressure is 1.5±0.5 kg / cm 2 ;

[0132] In the S3 water washing stage, the printed circuit board passing through the S2 degreasing stage is washed with tap water. The process parameters of the water washing stage are: This stage is immersion type, the water washing temperature is 25±1°C, the length of the water washing stage is 1.0 m, and the line speed is 2.0±0.2 m / min;

[0133] The S4 super-roughening section etches the printed circuit board that has passed through the S3 water-washing section. The process parameters of the super-roughening section are as follows: This section is of the spray type. The super-roughening chemical solution in the tank is the BTH-2085B super-roughening solution of Shenzhen Banming Technology Co., Ltd. The super-roughening solution is used as the original solution. The temperature in the tank is 25±5°C, the length of the super-roughening section is 3.0 m; the line speed is 3.0±0.2 m / min, and the spray pressure is 1.5±0.5 kg / cm 2 ; The super-roughening etching amount is 0.8 - 1.0 μm;

[0134] The S5 water-washing section washes the printed circuit board that has passed through the S4 super-roughening section with tap water. The process parameters of the water-washing section are as follows: This section is of the immersion type. The water-washing temperature is 25±1°C, the length of the water-washing section is 1.0 m, and the line speed is 2.0±0.2 m / min;

[0135] The S6 hydrochloric acid-washing section hydrochloric acid-washes the printed circuit board that has passed through the S5 water-washing section. The process parameters of the hydrochloric acid-washing section are as follows: This section is of the spray type. The mass concentration of hydrochloric acid is 5.0%, the balance is tap water, the temperature is 25±1°C, and the length of the water-washing section is 2.0 m; the line speed is 2.0±0.2 m / min, and the pressure is 1.5±0.5 kg / cm 2 ;

[0136] The S7 water-washing section washes the printed circuit board that has passed through the S6 hydrochloric acid-washing section with tap water. The process parameters of the water-washing section are as follows: This section is of the immersion type. The water-washing temperature is 25±1°C, the length of the water-washing section is 1.0 m, and the line speed is 2.0±0.2 m / min;

[0137] The S8 surface treatment section performs surface treatment on the printed circuit board that has passed through the S7 water-washing section. The chemical solution used is the PCB inkjet printing pretreatment agent or PCB inkjet printing anti-diffusion agent of the embodiment / control example of the present invention, and it is used as the original solution; The process parameters of the surface treatment section are as follows: This section is of the immersion type, the temperature is 25±1°C, the length of the surface treatment section is 2.0 m; the line speed is 4.0±0.2 m / min;

[0138] The S9 water-washing section washes the printed circuit board that has passed through the S8 surface treatment section with tap water. The process parameters of the water-washing section are as follows: This section is of the immersion type. The water-washing temperature is 25±1°C, the length of the water-washing section is 1.0 m, and the line speed is 2.0±0.2 m / min;

[0139] The S10 drying section dries the circuit board after the S9 water-washing section 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 line speed is 4.0±0.2 m / min;

[0140] The S11 inkjet printing section performs inkjet and curing on the printed circuit board after the S10 drying section process. The ink model used is H-9100 of Shenzhen Rongda Photosensitive Technology Co., Ltd. The process parameters of the inkjet printing section are as follows: the printing process is carried out in a dust-free environment, the printing temperature is 25±0.5°C, and the curing method is ultraviolet UV curing.

[0141] The performance of the PCB inkjet printing pretreatment agent or PCB inkjet printing anti-diffusion agent in the above Embodiments 1-7 and Comparative Examples 1-15 of the present invention is analyzed from the following three aspects:

[0142] 1) Anti-diffusion performance. The specific operation is as follows: Use a contact angle measuring instrument to measure the contact angles of the copper surface and the substrate surface of the printed circuit board with the ink after inkjet printing. The larger the contact angle, the better the effect of the pretreatment agent;

[0143] 2) Adhesion performance. It is tested by the 3M tape cross-cut test method. The specific operation is as follows: After the ink on the surface of the S11 inkjet printing section is cured, use a cross-cut tool to vertically cut on the surface of the PCB board with an ink coating on the PCB surface to form a grid-like scratch with 5*5 grid squares; Slowly and evenly paste the 3M600 test tape on the cross-cut area so that the tape is closely adhered to the ink surface; After standing for 1 minute, use tweezers to evenly tear off the tape and observe the ink peeling off in the cross-cut area.

[0144] Rating is carried out according to the detection standard of ISO2409, etc.:

[0145] Grade 0: The edges of the cuts are completely smooth, and no ink peels off at the grid edges;

[0146] Grade 1: A little ink peels off at the intersections of the cuts, but the peeling area does not exceed 5%;

[0147] Grade 2: Ink peels off at the edges and intersections of the cuts, and the peeling area is between 5% and 15%;

[0148] Grade 3: The ink has obvious peeling along the edges of the cuts, and the ink peeling area of some squares is between 15% and 35%;

[0149] Grade 4: The ink peels off in a large area, and the ink peeling area of most squares is between 35% and 65%;

[0150] Grade 5: The ink almost completely peels off, and the peeling area exceeds 65%;

[0151] The test result is required to reach Grade 0 or Grade 1 to be qualified;

[0152] 3) Print line integrity evaluation. The specific operation is as follows: Take a copper foil board and a substrate board with a size of 50*50 cm, and use the PCB inkjet printing pretreatment agent or the PCB inkjet printing anti-diffusion agent of the above-mentioned examples and comparative examples. According to the specific process flow of the fine PCB pattern inkjet printing of the present invention, print ink lines with a width of 30 μm on the copper foil board and the substrate board respectively, and observe whether there are open circuits in the ink lines and whether the line shapes are uniform and neat.

[0153] The performance test results of the PCB inkjet printing pretreatment agents of Examples 1-7 are shown in Table 1:

[0154]

[0155] The ink line on the copper surface of Example 1 is as Figure 1 shown; the ink line on the substrate surface of Example 1 is as Figure 2 shown.

[0156] It can be seen from the test results of Examples 1-7 in Table 1 that the PCB inkjet printing pretreatment agent of the present invention can form a uniform organic layer on both the copper surface and the substrate surface of the circuit board. This organic layer can not only effectively reduce the surface tension of the copper surface and the substrate surface, prevent the sprayed ink from spreading on the PCB surface, but also promote the uniform arrangement of the ink, which is beneficial to the formation of stable and neat linear ink; in the contact angle test, the contact angles between the copper surface, the substrate surface and the ink are all greater than 80°; in the adhesion test, the adhesion grades of the ink to the copper surface and the substrate surface are both Grade 0; in the line integrity test, when printing 30-μm ink lines on the copper surface and the substrate surface, the lines remain complete and uniform, which is applicable to the fine line inkjet printing process.

[0157] The performance test results of the PCB inkjet printing pretreatment agents or PCB inkjet printing anti-diffusion agents of Comparative Examples 1-15 are shown in Table 2:

[0158]

[0159] The ink line on the copper surface of Comparative Example 1 is as Figure 3 shown; the ink line on the substrate surface of Comparative Example 1 is as Figure 4 shown.

[0160] The differences between the PCB inkjet printing pretreatment agents of Comparative Examples 1-5 and Example 1 are that they lack the anti-diffusion agent, wetting agent, leveling agent, dispersant, and cosolvent single components respectively. The test results in Table 2 show that the anti-diffusion agent helps to improve the aggregation of the solder mask printing ink on the copper surface and the substrate surface, avoiding the diffusion of the ink to the surrounding areas. If the anti-diffusion agent is missing in the component, the ink contact angle on the copper surface and the substrate surface will be greatly reduced, and the ink cannot stand up on the PCB surface, which will also affect the adhesion and the circuit integrity; the three components of the wetting agent, leveling agent, and dispersant can improve the dispersibility, fluidity, and uniformity of each component in the pretreatment agent, ensuring that the active substances act evenly and quickly on the PCB surface. After missing one of the wetting agent, leveling agent, and dispersant, the test results of the ink contact angle, adhesion, and circuit integrity will all decline. It can be seen that the whole system needs the synergistic effect of the three to complete together; the cosolvent is used to dissolve the components that are poorly soluble in water to form a relatively stable solution. If this component is missing, the solution stable system cannot be formed, and the test results decline significantly. From the comparison of the test results of Example 1 and Comparative Examples 1-5, it can be seen that the PCB inkjet printing pretreatment agent of the present invention is the effect formed by the combined action of the five components of the anti-diffusion agent, wetting agent, leveling agent, dispersant, and cosolvent, and none of them can be missing.

[0161] For the PCB inkjet printing pretreatment agents of Comparative Examples 6-10, the concentrations of the anti-diffusion agent, wetting agent, leveling agent, dispersant, and cosolvent are respectively higher than the upper limit of the concentration of the PCB inkjet printing pretreatment agent of the present invention. The test results in Table 2 show that compared with Examples 1-5, when the concentrations of the anti-diffusion agent, wetting agent, leveling agent, dispersant, and cosolvent are too high, the influence of the test results changes little, indicating that too high a concentration has little effect on the surface energy of forming the organic layer on the PCB surface. The test results of the ink contact angle, adhesion, and circuit integrity are all close to those of the examples. However, too high a concentration will increase the cost of the potion. Considering from the cost factor, the concentrations of these five components in the anti-diffusion liquid agent of the present invention should not be too high, and the normal effect of the potion can be ensured within the concentration range of the examples.

[0162] The test results of Comparative Examples 11-14 show that the anti-diffusion agent, wetting agent, leveling agent, and dispersant with different types of branched-chain functional groups will also affect the performance of the PCB inkjet printing pretreatment agent of the present invention, and the effect substitution cannot be achieved, and the test effects of the ink contact angle, adhesion, and circuit integrity are poor.

[0163] The test results of Comparative Example 15 show that the existing PCB inkjet printing anti-diffusion agent used for PCB inkjet printing has a worse effect than the PCB inkjet printing pretreatment agent of the present invention. The PCB inkjet printing pretreatment agent of the present invention has better anti-diffusion performance, ink adhesion on the copper surface and the substrate surface of the circuit board, and is applicable to more fine inkjet printing circuits.

[0164] In summary, the pretreatment agent for PCB inkjet printing provided by the present invention can be used in the surface treatment process of the fine PCB pattern inkjet printing process, and can form a uniform organic layer on the copper surface and the substrate surface of the circuit board. This organic layer can not only effectively reduce the surface tension of the copper surface and the substrate surface, prevent the inkjet ink from spreading on the PCB surface, but also promote the uniform arrangement of the ink, which is beneficial to the formation of stable and neat linear ink, and improve the product yield of the fine circuit inkjet printing process.

[0165] As described above, 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 shall be subject to the protection scope of the claims.

Claims

1. A PCB inkjet printing pre-treatment agent, characterized in that: It is composed of the following components in mass concentration: Anti-diffusion agent 0.1-0.5%, Wetting agent 0.1-0.5%, Leveling agent 0.2-1.0%, Dispersant 0.5-2.5%, Solvent 0.1-3.0%, The balance is water; The anti-diffusion agent is a fluorobenzenethiophenol compound, the wetting agent is a polyethylene glycol acrylate compound, the homogenizing agent is a carboxylic acid phenyl ester compound, the dispersant is a carboxybenzocrown ether compound, and the cosolvent is a pinacol ester compound.

2. The PCB inkjet printing pre-treatment agent according to claim 1, characterized in that: The anti-diffusion agent is selected from at least one of 2,4-difluorobenzenethiol, 3,4-difluorobenzenethiol and 3,5-difluorobenzenethiol.

3. The PCB inkjet printing pre-treatment agent according to claim 1, characterized in that: The wetting agent is selected from at least one of methoxy polyethylene glycol acrylate, polyethylene glycol methacrylate and polyethylene glycol monoacrylate.

4. The PCB inkjet printing pre-treatment agent according to claim 1, characterized in that: The homogenizer is selected from at least one of diphenyl phenylphosphonate, diphenyl malonate and benzyl glycolate.

5. The PCB inkjet printing pre-treatment agent according to claim 1, characterized in that: The dispersant is selected from at least one of 4'-carboxybenzo-15-crown-5-ether and 4'-carboxybenzo-18-crown-6-ether.

6. The PCB inkjet printing pre-treatment agent according to claim 1, characterized in that: The cosolvent is selected from at least one of 6-quinolineboronic acid pinacol ester and 4-benzylphenylboronic acid pinacol ester.

7. The method for preparing a PCB inkjet printing pre-treatment agent according to any one of claims 1 to 6, characterized in that: The anti-diffusion agent, wetting agent, homogenizing agent, dispersant, co-solvent and water are placed in a reaction container, mixed evenly at 55-65° C., and cooled to room temperature to obtain the PCB inkjet printing pre-treatment agent.

8. A PCB inkjet printing method, characterized in that: The following steps are involved: Surface treatment: soak the PCB in the PCB inkjet printing pre-treatment agent as described in any one of claims 1 to 6 for 1.5 to 3 minutes; Inkjet printing: Inkjet and cure the surface treated PCB.

9. The PCB inkjet printing method according to claim 8, characterized in that: Before surface treatment, ultra-roughening treatment is also included: ultra-roughening etching is performed on the PCB.

10. The PCB inkjet printing method according to claim 9, characterized in that: The ultra-roughening etching amount is 0.8-1.0 μm.

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