A color difference control method of a mini LED PCB

Abstract

The application discloses a color difference control method of a Mini LED PCB, which comprises a volcanic ash grinding plate consistency treatment and a printing consistency treatment, the volcanic ash grinding plate consistency treatment comprising: treating a PCB substrate by using a modified volcanic ash solution in combination with grinding and brushing, and the preparation method of the modified volcanic ash comprising: after the volcanic ash is finely ground, acidizing treatment is performed, then water washing, drying, immersion in a water-soluble cellulose ether water suspension, steaming after the immersion is completed, flushing off the surface material of the volcanic ash, and drying; the printing consistency treatment comprising: spraying a silane solution on the edge of a silk screen plate, and performing anti-solder silk screen printing after drying. The volcanic ash grinding plate consistency treatment can obtain a roughness with good uniformity on the surface of the substrate, and the water washing in combination with acetic acid cleaning can effectively remove impurities on the surface of the plate; then the printing consistency treatment can reduce the influence of ink accumulation on the edge of the silk screen plate on the uniformity of ink printing, and the above operation can comprehensively control the color difference of the PCB, and the process is simple.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of circuit boards, and particularly relates to a color difference control method for a Mini LED PCB. BACKGROUND

[0002] Mini LED (small light-emitting diode) is small in size and has a special cutting characteristic, and can achieve a high-curved backlight form in combination with a soft substrate. The Mini LED PCB has a local dimming design and better color. There is a problem of optical consistency in the Mini LED PCB, and optimizing the color difference DE tolerance range of the ink color of a printed circuit board (PCB) board surface becomes a cornerstone for improving the optical consistency. The smaller the DE tolerance range is, the better the optical consistency is. At present, the DE tolerance range is mainly controlled by controlling the color difference of the solder mask ink in the industry. Meanwhile, the processes such as solder mask pretreatment (mechanical grinding of the board) and solder mask screen printing involved in the PCB manufacturing process are easy to cause problems such as color difference (non-uniform roughening degree) of the PCB board surface and color difference of the printed ink, resulting in color difference of the PCB.

[0003] The solder mask pretreatment is to remove the oxidation layer of the copper surface of the circuit board, clean the surface of the circuit board and roughen the copper surface before solder mask, so as to enhance the bonding force between the ink and the solder mask layer. The commonly used solder mask pretreatment method at present is generally a volcano ash grinding plate treatment. This method uses volcano ash as an abrasive to roughen the substrate, which is simple and environmentally friendly, but the roughening effect and uniformity are not enough, resulting in uneven roughening and insufficient roughness of the PCB substrate surface obtained by the pretreatment, and causing color difference.

[0004] In addition, in order to control the color consistency in the prior art, the screen plate is treated with oil collection during screen printing every other preset printing cycle, so that the viscosity of the ink on the screen plate is within the preset viscosity range, and the color difference between the LED printed circuit boards is small. The principle of this method is that because the squeegee moves back and forth on the screen plate, some ink is scraped on the edge of the screen plate. Because the ink has a certain fluidity, but the fluidity is low, this will cause the ink at the edge of the screen plate to have a tendency to flow to the center of the screen plate, but the speed of the ink flowing to the center of the screen plate is relatively slow, further causing a part of the ink to be exposed to the air for a long time. The viscosity of this part of the ink is quite different from the viscosity of the ink near the center of the screen plate. The ink flowing from the edge of the screen plate to the center of the screen plate will cause a large change in the viscosity of the original ink at the center of the screen plate, thereby affecting the color difference between the circuit surfaces of the plurality of LED substrates. Therefore, by scraping the ink at the edge of the screen plate, the ink at the edge of the screen plate is well mixed with the ink near the center of the screen plate, so that the viscosity difference between the ink at the edge of the screen plate and the ink near the center of the screen plate is maintained within a small range, the amount of ink exposed to the air for a long time is reduced, and the color difference between the circuit surfaces of the plurality of LED substrates is further reduced.

[0005] Although this method can control the viscosity of the ink to control the color difference, it is troublesome to operate, and oil collection treatment is required every other preset printing cycle, which is inconvenient for actual production.

[0006] In summary, how to provide a color difference control method for Mini LED PCB, by controlling the consistency of pre-soldering treatment and soldering ink printing, to solve the problem of PCB color difference control, is a problem that needs to be solved. SUMMARY

[0007] The purpose of the present application is to overcome the shortcomings of the prior art, provide a color difference control method for Mini LED PCB, modify the volcanic ash by volcanic ash grinding plate consistency treatment, obtain a roughness with good uniformity on the substrate surface, and effectively remove impurities on the plate surface by water washing combined with acetic acid cleaning; then the edge of the screen plate is treated by spraying silane solution, which reduces the influence of ink accumulation on the edge of the screen plate on the uniformity of ink printing. The above operations can comprehensively control the color difference of the PCB.

[0008] A color difference control method for Mini LED PCB, comprising volcanic ash grinding plate consistency treatment, the volcanic ash grinding plate consistency treatment comprising: treating the PCB substrate by using modified volcanic ash solution and grinding and brushing.

[0009] The preparation method of the modified volcanic ash comprises the following steps: after the volcanic ash is finely ground (200-400 mesh), acid treatment (soaking in 0.5-3 mol / L sulfuric acid for 10-30 min) is performed, then water washing, drying, and then dipping in a water suspension containing 1-15% (mass percentage) water-insoluble cellulose ether for 20-60 min; after the dipping is completed, steam drying is performed, the surface material of the volcanic ash is washed off with water, and then drying is performed.

[0010] Preferably, the concentration of the modified volcanic ash solution (in terms of the mass percentage of the modified volcanic ash) is 12-20%, and the grinding plate speed is 1.5-2.5 m / min.

[0011] Preferably, the water-insoluble cellulose ether is one or any combination of carboxymethyl cellulose calcium, cellulose acetate, triacetate cellulose, and ethyl cellulose, and more preferably, the water-insoluble cellulose ether is carboxymethyl cellulose calcium. The amount of the water-insoluble cellulose ether is 1-6% of the mass of the volcanic ash.

[0012] Preferably, the modified volcanic ash solution further comprises a polyol, and the polyol is dipropylene glycol, glycerol, polyethylene glycol, or glucose, and more preferably, the polyol is dipropylene glycol. The amount of the polyol is 0.05-0.3 times the mass of the modified volcanic ash.

[0013] Preferably, the color difference control method further comprises a printing consistency treatment, and the printing consistency treatment comprises: spraying a silane solution (mass concentration of 10-30%) on the edge of the screen plate, and then performing anti-welding screen printing after drying.

[0014] Preferably, the edge of the screen plate specifically refers to a position range extending inward from the screen frame to a distance of 3-6 cm from the screen frame.

[0015] The silane is one or any combination of dipiperidinyl diethoxysilane, urea propyl triethoxysilane, gamma-aminopropyl trimethoxysilane, and gamma-aminopropyl triethoxysilane, and more preferably, the silane is dipiperidinyl diethoxysilane. The spraying amount of the silane is 0.01-0.08 g / cm 2 .

[0016] The application further provides a cleaning process in the color difference control method of the Mini LED PCB, and the PCB substrate is cleaned after the volcanic ash grinding plate consistency treatment. The cleaning steps comprise: first, water washing (water flow of 5-10 L / min, to remove most impurities), then cleaning with an acetic acid aqueous solution (mass fraction of 1-15%) at 30-50℃, and then water washing (water flow of 10-20 L / min) and drying.

[0017] Preferably, the acetic acid aqueous solution cleaning conditions comprise:

[0018] First, at 35-45℃, with 3-8% acetic acid aqueous solution at a flow rate of 2-5 L / min, normal pressure cleaning for 10-20 min;

[0019] Then, at 40-50℃, with 10-15% acetic acid aqueous solution at a flow rate of 4-6 L / min, normal pressure cleaning for 15-30 min;

[0020] Then, at 30-40℃, with 2-4% acetic acid aqueous solution at a flow rate of 10-20 L / min, pressure cleaning for 3-6 min, pressure is 3-5 kg / cm 3 , cleaning angle (the angle between the direction of the liquid sprayed by the gun and the substrate) is 30-60°;

[0021] Finally, at 30-35℃, with 1-3% acetic acid aqueous solution at a flow rate of 20-30 L / min, pressure cleaning for 2-4 min, pressure is 5-8 kg / cm 3 , cleaning angle is 60-80°.

[0022] Technical effects of the present application:

[0023] 1、The present application carries out the consistency treatment of the volcanic ash grinding plate for the PCB substrate, and the roughness with good uniformity is obtained on the surface of the substrate, which can effectively control the color difference of the circuit board. When the present application carries out the consistency treatment of the volcanic ash grinding plate, the volcanic ash is modified, first, water-insoluble cellulose ether is introduced into the porous structure of the volcanic ash, the water-insoluble cellulose ether is easy to swell and increase the volume in the volcanic ash solution, which helps to improve the contact angle when the volcanic ash as an abrasive roughens the substrate to form a hole, and improve the fitting force when the two are in contact, thereby improving the friction between the volcanic ash and the substrate, and the cellulose ether with adhesion can also improve the contact time between the volcanic ash and the substrate, and finally improve the uniformity of the roughening effect.

[0024] 2、When the present application carries out the consistency treatment of the volcanic ash grinding plate, polyol is also added to the modified volcanic ash solution, which can improve the dispersibility of the volcanic ash, thereby further improving the uniformity of the roughening effect. The polyol is preferably dipropyl glycerol, which can also control the combination of volcanic ash and water, thereby controlling the water swelling range of the cellulose ether in a more appropriate range. The swelling range of the cellulose ether in the pores of the volcanic ash needs to be moderate, too high swelling will make the cellulose ether swelling body too large to protrude out of the surface of the volcanic ash, which will reduce the hardness of the volcanic ash abrasive and affect the roughening effect, and too low swelling will reduce the contact surface between the cellulose ether swelling body and the substrate indentation, resulting in insufficient friction between the volcanic ash and the substrate, therefore, the swelling range of the cellulose ether in the pores of the volcanic ash needs to be controlled.

[0025] 3、The present application carries out printing consistency treatment on the PCB substrate, before silk screen printing solder resist ink, the edge of the silk screen plate is sprayed with silane solution treatment, so that the ink can be uniformly spread on the surface of the edge of the silk screen plate without external force, reducing the influence of ink accumulation on the edge of the silk screen plate on the uniformity of ink printing, so as to control the color difference.

[0026] The silane of the present application is preferably dipiperidinyl diethoxysilane, which can also delay the deterioration of the ink on the edge of the silk screen plate caused by long-term exposure to air (such as the appearance of hardened particles, lumps, etc.), maintaining the stability of the ink on the edge.

[0027] 4、After the modified volcanic ash solution is used for pre-treatment of the substrate before solder resist, the roughness of the substrate is increased, and the cellulose ether in the modified volcanic ash is easily left in the roughened pores due to its adhesion, which is difficult to remove completely by ordinary water washing, affecting the bonding force of the ink and the substrate. The present application uses gradient cleaning of acetic acid aqueous solution with different concentrations and different flow rates, and sets different cleaning pressures and cleaning angles, which can effectively remove the residual cellulose ether in the substrate.

[0028] The present application first uses a lower flow rate of acetic acid aqueous solution at normal pressure to promote the further swelling of cellulose ether, and then uses a high flow rate of acetic acid aqueous solution under pressure, and first cleans at a smaller cleaning angle, which prevents the swollen granular cellulose ether from being combined more tightly with the substrate under pressure, and promotes the separation of the swollen granular, and then cleans at a larger angle, which deeply cleans. DETAILED DESCRIPTION

[0029] The above scheme will be further described in combination with specific examples; it should be understood that these examples are used to illustrate the basic principles, main features and advantages of the present application, and the present application is not limited in scope by the following examples; the implementation conditions used in the examples can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0030] In the following examples, all raw materials are obtained from commercial sources or prepared by conventional methods in the art, unless otherwise specified.

[0031] Example 1

[0032] The present embodiment provides a color difference control method for Mini LED PCB, which comprises volcanic ash plate grinding consistency treatment:

[0033] The modified volcanic ash solution with a concentration of 15% (by mass of the modified volcanic ash) is used in combination with brushing to treat the PCB substrate at a brushing speed of 2 m / min. The modified volcanic ash is prepared by the following steps: after being finely ground (300 mesh), the volcanic ash is subjected to acid treatment (soaked in 1 mol / L sulfuric acid for 20 min), then washed with water, dried, and immersed in a water suspension containing 5% (by mass) calcium carboxymethyl cellulose for 40 min; after the immersion is completed, the volcanic ash is steamed dry, the surface material of the volcanic ash is washed off with water, and then dried. The amount of calcium carboxymethyl cellulose used is 3% of the mass of the volcanic ash.

[0034] The PCB substrate is washed using a conventional process after the consistency treatment of the volcanic ash. The solder mask screen printing is performed using a conventional method.

[0035] The remaining processes are performed using a conventional PCB processing process.

[0036] Example 2

[0037] The color difference control method of the Mini LED PCB provided in this example is different from that of Example 1 in that the calcium carboxymethyl cellulose is replaced by cellulose acetate.

[0038] Example 3

[0039] The color difference control method of the Mini LED PCB provided in this example is different from that of Example 1 in that the calcium carboxymethyl cellulose is replaced by ethyl cellulose.

[0040] Example 4

[0041] On the basis of Example 1, the modified volcanic ash solution further includes dipropyl glycerol.

[0042] The color difference control method of the Mini LED PCB provided in this example includes consistency treatment of the volcanic ash for grinding the PCB substrate:

[0043] The modified volcanic ash, dipropyl glycerol, and water are prepared into a modified volcanic ash solution, the concentration of the modified volcanic ash solution is 15%, and the amount of dipropyl glycerol used is 0.1 times the mass of the modified volcanic ash.

[0044] The modified volcanic ash solution is used in combination with brushing to treat the PCB substrate at a brushing speed of 2 m / min. The modified volcanic ash is prepared by the following steps: after being finely ground (300 mesh), the volcanic ash is subjected to acid treatment (soaked in 1 mol / L sulfuric acid for 20 min), then washed with water, dried, and immersed in a water suspension containing 5% (by mass) calcium carboxymethyl cellulose for 40 min; after the immersion is completed, the volcanic ash is steamed dry, the surface material of the volcanic ash is washed off with water, and then dried. The amount of calcium carboxymethyl cellulose used is 3% of the mass of the volcanic ash.

[0045] Embodiment 5

[0046] The embodiment provides a color difference control method of a Mini LED PCB, which is different from the embodiment 4 in that the carboxymethyl cellulose calcium is replaced by cellulose acetate.

[0047] Embodiment 6

[0048] The embodiment provides a color difference control method of a Mini LED PCB, which is different from the embodiment 4 in that the carboxymethyl cellulose calcium is replaced by cellulose triacetate.

[0049] Embodiment 7

[0050] The embodiment provides a color difference control method of a Mini LED PCB, which is different from the embodiment 4 in that the dipropyl glycerol is replaced by glycerol.

[0051] Embodiment 8

[0052] The embodiment provides a color difference control method of a Mini LED PCB, which is different from the embodiment 4 in that the dipropyl glycerol is replaced by polyethylene glycol.

[0053] Embodiment 9

[0054] The embodiment provides a color difference control method of a Mini LED PCB, which is different from the embodiment 4 in that the PCB substrate is cleaned after the consistency treatment of the volcanic ash grinding plate, and the cleaning step comprises the following steps: firstly, water washing (water flow is 7 L / min, and most impurities are removed), then cleaning by using an acetic acid aqueous solution, and then water washing (water flow is 15 L / min), and drying.

[0055] The acetic acid aqueous solution cleaning condition comprises the following steps:

[0056] firstly, 5% acetic acid aqueous solution is used for normal pressure cleaning at 3 L / min flow rate and 40℃ for 15 min;

[0057] then, 12% acetic acid aqueous solution is used for normal pressure cleaning at 5 L / min flow rate and 45℃ for 20 min;

[0058] then, 3% acetic acid aqueous solution is used for pressure cleaning at 15 L / min flow rate and 35℃ for 5 min, the pressure is 4 kg / cm 3 , and the cleaning angle (the angle between the liquid direction sprayed by the water gun and the substrate) is 45°;

[0059] finally, 2% acetic acid aqueous solution is used for pressure cleaning at 25 L / min flow rate and 32℃ for 3 min, the pressure is 6 kg / cm 3, the cleaning angle is 70°.

[0060] Embodiment 10

[0061] On the basis of Embodiment 9, this embodiment further includes a printing consistency treatment.

[0062] This embodiment provides a color difference control method of a Mini LED PCB, comprising:

[0063] 1. Volcanic ash grinding plate consistency treatment

[0064] The modified volcanic ash, dipropyl glycerol and water are prepared into a modified volcanic ash aqueous solution, the concentration of the modified volcanic ash aqueous solution is 15%, and the amount of dipropyl glycerol is 0.1 times the mass of the modified volcanic ash.

[0065] The modified volcanic ash aqueous solution is used to polish and brush the PCB substrate, and the grinding plate speed is 2 m / min. The preparation method of the modified volcanic ash comprises the following steps: after the volcanic ash is finely ground (300 mesh), acidification treatment is performed (soaked in 1 mol / L sulfuric acid for 20 min), then washed with water, dried, and immersed in a water suspension containing 5% (mass percent) calcium carboxymethyl cellulose for 40 min; after the immersion is completed, steam dry, wash off the surface material of the volcanic ash with water, and dry. The amount of calcium carboxymethyl cellulose is 3% of the mass of the volcanic ash.

[0066] 2. Substrate cleaning

[0067] After the volcanic ash grinding plate consistency treatment, the PCB substrate is cleaned, and the cleaning steps include: first, water washing (water flow 7 L / min, removing most of the impurities), then cleaning with an aqueous acetic acid solution, and then water washing (water flow 15 L / min), drying.

[0068] The aqueous acetic acid solution cleaning conditions include:

[0069] First, at 40℃, clean with 5% aqueous acetic acid solution at a flow rate of 3 L / min under normal pressure for 15 min;

[0070] Then, at 45℃, clean with 12% aqueous acetic acid solution at a flow rate of 5 L / min under normal pressure for 20 min;

[0071] Then, at 35℃, clean with 3% aqueous acetic acid solution at a flow rate of 15 L / min under pressure for 5 min, the pressure is 4 kg / cm 3 , the cleaning angle (the angle between the direction of the liquid sprayed by the water gun and the substrate) is 45°;

[0072] Finally, at 32℃, clean with 2% aqueous acetic acid solution at a flow rate of 25 L / min under pressure for 3 min, the pressure is 6 kg / cm 3, the cleaning angle is 70°.

[0073] 3. Print uniformity processing

[0074] Spray dipyridyl diethoxysilane solution (mass concentration of 20%) on the edge of the screen plate, the spraying amount of dipyridyl diethoxysilane is 0.05 g / cm 2 , and then the conventional method is used for anti-welding screen printing.

[0075] Specifically, the edge of the screen plate refers to a position range extending inward from the screen frame to a distance of 3-6 cm from the screen frame.

[0076] Example 11

[0077] The embodiment provides a color difference control method of a Mini LED PCB, comprising:

[0078] 1. Volcanic ash grinding plate uniformity processing

[0079] The modified volcanic ash, dipropyl glycerol and water are prepared into a modified volcanic ash aqueous solution, the concentration of the modified volcanic ash aqueous solution is 12%, and the amount of polyol is 0.05 times the mass of the modified volcanic ash.

[0080] The modified volcanic ash aqueous solution is used for grinding and brushing the PCB substrate, and the grinding rate is 1.5 m / min. The preparation method of the modified volcanic ash comprises the following steps: after the volcanic ash is finely ground (200 mesh), acidification treatment is performed (soaking in 0.5 mol / L sulfuric acid for 30 min), then water washing, drying, and dipping in a water suspension containing 1% (mass percent) carboxymethyl cellulose calcium for 60 min; after the dipping is completed, steam drying is performed, the surface material of the volcanic ash is washed off with water, and drying is performed.

[0081] 2. Substrate cleaning

[0082] After the volcanic ash grinding plate uniformity processing, the PCB substrate is cleaned, and the cleaning steps include: first water washing (water flow of 5 L / min, to remove most of the impurities), then cleaning with acetic acid aqueous solution, and then water washing (water flow of 10 L / min), drying.

[0083] The acetic acid aqueous solution cleaning conditions include:

[0084] First, 3% acetic acid aqueous solution is used for normal pressure cleaning at 35°C and a flow rate of 2 L / min for 20 min;

[0085] Then, 10% acetic acid aqueous solution is used for normal pressure cleaning at 40°C and a flow rate of 4 L / min for 30 min;

[0086] Then, at 30°C, the PCB substrate is cleaned with 2% acetic acid water solution at a flow rate of 10 L / min for 6 min, with a pressure of 5 kg / cm 3 and an angle of 30°.

[0087] Finally, at 30°C, the PCB substrate is cleaned with 1% acetic acid water solution at a flow rate of 20 L / min for 4 min, with a pressure of 8 kg / cm 3 and an angle of 60°.

[0088] 3. Print uniformity treatment

[0089] The edges of the screen plate are sprayed with a solution of dipiperidinyl diethoxysilane (10% by mass), and the amount of dipiperidinyl diethoxysilane sprayed is 0.01 g / cm 2 After spraying, the screen plate is dried, and then the screen plate is subjected to conventional solder mask printing.

[0090] The remaining processes are performed using conventional PCB processing technology.

[0091] Example 12

[0092] On the basis of Example 9, the PCB substrate is cleaned after the ash screen plate uniformity treatment.

[0093] The present example provides a color difference control method for a Mini LED PCB, comprising:

[0094] 1. Ash screen plate uniformity treatment

[0095] Modified ash, dipropyl triol, and water are mixed to form a modified ash water solution, and the concentration of the modified ash water solution is 20%, and the amount of polyol is 0.3 times the mass of the modified ash.

[0096] The modified ash water solution is used to treat the PCB substrate by rubbing and brushing, and the rubbing and brushing rate is 2.5 m / min. The preparation method of the modified ash includes the following steps: after the ash is finely ground (400 mesh), acidification treatment is performed (soaked in 2 mol / L sulfuric acid for 10 min), then washed with water, dried, and immersed in a water suspension containing 10% (mass percent) calcium carboxymethyl cellulose for 20 min; after the immersion is completed, the surface material of the ash is steamed and washed off with water, and then dried. The amount of calcium carboxymethyl cellulose is 6% of the mass of the ash.

[0097] 2. Substrate cleaning

[0098] After the consistency treatment of the volcanic ash grinding plate, the PCB substrate is cleaned, and the cleaning steps include: first, water washing (water flow 10 L / min, removing most impurities), then cleaning with acetic acid solution, and then water washing (water flow 20 L / min), drying.

[0099] The cleaning conditions of the acetic acid solution include:

[0100] First, at 45℃, 8% acetic acid solution with a flow rate of 5 L / min is cleaned under normal pressure for 10 min;

[0101] Then, at 50℃, 15% acetic acid solution with a flow rate of 6 L / min is cleaned under normal pressure for 15 min;

[0102] Then, at 40℃, 4% acetic acid solution with a flow rate of 20 L / min is cleaned under pressure for 3 min, and the pressure is 3 kg / cm 3 The cleaning angle (the angle between the direction of the liquid sprayed by the water gun and the substrate) is 60°;

[0103] Finally, at 35℃, 3% acetic acid solution with a flow rate of 30 L / min is cleaned under pressure for 2 min, and the pressure is 5 kg / cm 3 The cleaning angle is 80°.

[0104] 3. Print consistency treatment

[0105] Spray dipyridyl diethoxysilane solution (mass concentration 30%) at the edge of the silk screen plate, the amount of dipyridyl diethoxysilane sprayed is 0.08 g / cm 2 , and then dried, and then the conventional method is used for solder mask screen printing.

[0106] The remaining processes use conventional PCB processing technology.

[0107] Example 13

[0108] The embodiment provides a color difference control method of a Mini LED PCB, which is different from example 10 in that dipyridyl diethoxysilane is replaced by urea propyl triethoxysilane.

[0109] Example 14

[0110] The embodiment provides a color difference control method of a Mini LED PCB, which is different from example 10 in that dipyridyl diethoxysilane is replaced by gamma-aminopropyl trimethoxysilane.

[0111] Comparative example 1

[0112] The difference between the present comparative example and Example 1 is that the ordinary volcanic ash (300 mesh) is directly used for treatment without modification of the volcanic ash.

[0113] Comparative Example 2

[0114] The difference between the present comparative example and Example 1 is that the carboxymethyl cellulose calcium is replaced by xanthan gum.

[0115] Comparative Example 3

[0116] The difference between the present comparative example and Example 1 is that the carboxymethyl cellulose calcium is replaced by starch.

[0117] Comparative Example 4

[0118] The difference between the present comparative example and Example 1 is that the carboxymethyl cellulose calcium is replaced by bentonite.

[0119] Comparative Example 5

[0120] The difference between the present comparative example and Example 1 is that the amount of carboxymethyl cellulose calcium is 0.5% of the mass of the volcanic ash.

[0121] Comparative Example 6

[0122] The difference between the present comparative example and Example 1 is that the amount of carboxymethyl cellulose calcium is 7% of the mass of the volcanic ash.

[0123] Comparative Example 7

[0124] The difference between the present comparative example and Example 4 is that the dipropyl glycerol is replaced by the anionic surfactant sodium lignosulfonate.

[0125] Comparative Example 8

[0126] The difference between the present comparative example and Example 4 is that the dipropyl glycerol is replaced by the nonionic surfactant nonylphenol polyoxyethylene ether.

[0127] Comparative Example 9

[0128] The difference between the present comparative example and Example 9 is that the PCB substrate is cleaned after the consistency treatment of the volcanic ash grinding plate, and the cleaning step does not include the cleaning with the aqueous acetic acid solution.

[0129] Comparative Example 10

[0130] The difference between the present comparative example and Example 9 is that the cleaning condition of the aqueous acetic acid solution includes:

[0131] First, the 12% aqueous acetic acid solution is cleaned at 45°C at a flow rate of 5 L / min under normal pressure for 20 min;

[0132] Then, at 35°C, a 3% acetic acid aqueous solution was pressure-washed at a flow rate of 15 L / min for 5 min, the pressure was 4 kg / cm3, and the washing angle was 45°.

[0133] Finally, at 32°C, a 2% acetic acid aqueous solution was pressure-washed at a flow rate of 25 L / min for 3 min, the pressure was 6 kg / cm3, and the washing angle was 70°.

[0134] Comparative Example 11

[0135] The difference between this comparative example and Example 9 is that the acetic acid aqueous solution washing conditions include:

[0136] First, at 40°C, a 5% acetic acid aqueous solution was atmospheric pressure-washed at a flow rate of 3 L / min for 15 min;

[0137] Then, at 35°C, a 3% acetic acid aqueous solution was pressure-washed at a flow rate of 15 L / min for 5 min, the pressure was 4 kg / cm3, and the washing angle was 45°.

[0138] Finally, at 32°C, a 2% acetic acid aqueous solution was pressure-washed at a flow rate of 25 L / min for 3 min, the pressure was 6 kg / cm3, and the washing angle was 70°.

[0139] Comparative Example 12

[0140] The difference between this comparative example and Example 9 is that the acetic acid aqueous solution washing conditions include:

[0141] First, at 40°C, a 5% acetic acid aqueous solution was atmospheric pressure-washed at a flow rate of 3 L / min for 15 min;

[0142] Next, at 45°C, a 12% acetic acid aqueous solution was atmospheric pressure-washed at a flow rate of 5 L / min for 20 min;

[0143] Finally, at 32°C, a 2% acetic acid aqueous solution was pressure-washed at a flow rate of 25 L / min for 3 min, the pressure was 6 kg / cm3, and the washing angle was 70°.

[0144] Comparative Example 13

[0145] The difference between this comparative example and Example 9 is that the acetic acid aqueous solution washing conditions include:

[0146] First, at 40°C, a 5% acetic acid aqueous solution was atmospheric pressure-washed at a flow rate of 3 L / min for 15 min;

[0147] Next, at 45°C, a 12% acetic acid aqueous solution was atmospheric pressure-washed at a flow rate of 5 L / min for 20 min;

[0148] Then, the substrate was cleaned with 3% acetic acid aqueous solution at a flow rate of 15 L / min at 35°C for 5 min under a pressure of 4 kg / cm3, and the cleaning angle (the angle between the direction of liquid sprayed from the nozzle and the substrate) was 45°.

[0149] Comparative Example 14

[0150] The difference between this comparative example and Example 9 is that the cleaning angle in the acetic acid aqueous solution cleaning condition was changed from 45° to 20°.

[0151] Comparative Example 15

[0152] The difference between this comparative example and Example 9 is that the cleaning angle in the acetic acid aqueous solution cleaning condition was changed from 45° to 70°.

[0153] Comparative Example 16

[0154] The difference between this comparative example and Example 9 is that the cleaning angle in the acetic acid aqueous solution cleaning condition was changed from 70° to 50°.

[0155] Comparative Example 17

[0156] The difference between this comparative example and Example 9 is that the cleaning angle in the acetic acid aqueous solution cleaning condition was changed from 70° to 90°.

[0157] Comparative Example 18

[0158] The difference between this comparative example and Example 10 is that, in the print uniformity treatment, the dipyrridyl diethoxysilane solution was sprayed on the entire screen plate.

[0159] Comparative Example 19

[0160] The difference between this comparative example and Example 10 is that, in the print uniformity treatment, the dipyrridyl diethoxysilane solution was sprayed on the center of the screen plate.

[0161] Comparative Example 20

[0162] The difference between this comparative example and Example 10 is that, in the print uniformity treatment, the amount of dipyrridyl diethoxysilane sprayed was 0.005 g / cm 2 .

[0163] Comparative Example 21

[0164] The difference between this comparative example and Example 10 is that, in the print uniformity treatment, the amount of dipyrridyl diethoxysilane sprayed was 0.1 g / cm 2 .

[0165] I. Detection of the color difference value ΔE of the PCB

[0166] The color difference value DE of the PCB was detected by the color difference control method of the application examples 1-14 and the comparative examples 1-21, and the results are shown in Table 1 below.

[0167] Table 1

[0168]

[0169]

[0170] As can be seen from Table 1, the color difference value DE of the Mini LED PCB obtained by the color difference control method of the application examples 1-14 is controlled to be less than 1.0, and the color difference control effect of the PCB is good.

[0171] Comparing application examples 1-3, it can be seen that the modification effect of the calcium carboxymethyl cellulose on the volcanic ash is good. Comparing application examples 4-8, it can be seen that the effect of adding dipropylene glycol to the modified volcanic ash aqueous solution while modifying the volcanic ash is good. Comparing application examples 10, 13-14, it can be seen that the effect of using dipiperidinyl diethoxysilane for printing consistency treatment is good.

[0172] Application example 1 uses modified volcanic ash aqueous solution for volcanic ash grinding plate consistency treatment, and the DE is 0.72. On the basis of application example 1, application example 4 adds dipropylene glycol to the modified volcanic ash aqueous solution, further reducing the DE to 0.56. On the basis of application example 4, application example 9 cleans the PCB substrate after the volcanic ash grinding plate consistency treatment, and uses acetic acid aqueous solution for cleaning under specific conditions, reducing the influence of cellulose ether residue in the modified volcanic ash aqueous solution on the substrate, so that the DE is reduced to 0.38. On the basis of application example 9, application example 10 performs printing consistency treatment, reduces the ink accumulation at the edge of the screen plate, and further reduces the DE to 0.15.

[0173] Compared with application example 1, comparative examples 1-6 use ordinary volcanic ash and change the modification method of the volcanic ash; compared with application example 4, comparative examples 7-8 change the type of polyol; compared with application example 9, comparative examples 9-17 change the cleaning process; compared with application example 10, comparative examples 18-21 change the spraying position and amount of the silane solution; and the results of application examples 1-20 are reduced.

[0174] II. Effect of PCB Volcanic Ash Grinding Plate Consistency Treatment

[0175] 1. Plate surface roughness

[0176] The roughness of the PCB board surface after the consistency treatment of the volcanic ash grinding plate of the present application examples 1-8 and comparative examples 1-8 was tested to evaluate the effect of the consistency treatment of the volcanic ash grinding plate of the present application. A plurality of PCB board samples were randomly taken, the surface roughness Ra was measured, the average value and the standard deviation of Ra were calculated, and the results are shown in Table 2 below.

[0177] Table 2

[0178]

[0179] As can be seen from Table 2, the roughness Ra of the PCB board surface after the consistency treatment of the volcanic ash grinding plate of the present application examples 1-8 is higher in the range of 0.24-0.38 μm.

[0180] Compared with the ordinary volcanic ash used in comparative example 1, the roughness of examples 1-3 is increased and the standard deviation is reduced, indicating that the modification of the volcanic ash can improve the roughness of the board surface and the roughness uniformity. Among them, the modification effect of example 1 using carboxymethyl cellulose calcium is better.

[0181] On the basis of example 1, example 4 further improves the roughness of the board surface and the roughness uniformity by adding dipropyl glycerol to the modified volcanic ash aqueous solution.

[0182] Compared with example 1, comparative examples 2-6 change the modification method of the volcanic ash; compared with example 4, comparative examples 7-8 change the type of polyol; and the roughening effect is poor.

[0183] 2. Hardness of modified volcanic ash

[0184] The modified volcanic ash solution obtained by different methods of examples 1, 4-8 and comparative examples 7-8 was stirred for 30 min, then the (modified) volcanic ash was taken out, and its hardness was measured and compared with the hardness of the volcanic ash raw material to evaluate the effect of adding polyol to the modified volcanic ash solution on the (modified) volcanic ash, and the results are shown in Table 3.

[0185] Table 3

[0186]

[0187] As shown in Table 3, compared with the raw volcanic ash, the hardness of the modified volcanic ash is reduced to 5 due to the influence of the carboxymethyl cellulose calcium expansion body in Example 1. On the basis of Example 1, dimeric glycerol is added to the modified volcanic ash aqueous solution in Example 4, so as to control the expansion range of the carboxymethyl cellulose calcium, and the hardness of the modified volcanic ash is equivalent to that of the raw volcanic ash. As shown in Comparative Examples 4-8, the hardness of the modified volcanic ash is reduced when the carboxymethyl cellulose calcium is used to modify the volcanic ash and the dimeric glycerol is added to the modified volcanic ash aqueous solution.

[0188] As shown in Table 5, compared with Example 4, the hardness of the modified volcanic ash is reduced when different surfactants are used to replace the dimeric glycerol in Comparative Examples 7-8.

[0189] III. Cleaning process effect of PCB after consistency treatment of volcanic ash grinding plate

[0190] PCB is cleaned after consistency treatment of volcanic ash grinding plate according to the methods of Examples 4, 9-12 and Comparative Examples 9-17, respectively, and the residual situation of impurities such as particles on the board surface is observed after cleaning. The results are shown in Table 4.

[0191] Table 4

[0192]

[0193] As shown in Table 4, compared with Example 4, the cleaning effect is better and there is no obvious residue when the specific cleaning process is used to clean the PCB after consistency treatment of volcanic ash grinding plate in Examples 9-12.

[0194] As shown in Table 5, compared with Example 9, the cleaning effect is worse when the cleaning steps are changed in Comparative Examples 9-17.

[0195] IV. Printing consistency treatment effect

[0196] Printing consistency treatment is performed according to the methods of Examples 10-14 and Comparative Examples 18-21, the ink accumulation and metamorphic situation (whether there are particle precipitation, delamination or discoloration phenomenon) of the screen plate edge are observed, and the conventional anti-welding screen printing process without printing consistency treatment is compared. The results are shown in Table 5.

[0197] Table 5

[0198]

[0199] As shown in Table 5, compared with conventional screen printing processes (without printing consistency treatment), after printing consistency treatment in Examples 10-12 of this invention, no obvious ink accumulation or ink deterioration was observed at the edges of the screen printing plates. Compared with Example 12 (using dipiperidyldiethoxysilane), although no obvious ink accumulation was observed in Examples 13 (using ureapropyltriethoxysilane) and 14 (using γ-aminopropyltrimethoxysilane), slight deterioration was observed, indicating that dipiperidyldiethoxysilane can also improve the ink deterioration at the edges of the screen printing plates.

[0200] Compared with Example 10, Comparative Examples 18-21 changed the spraying location and spraying amount of the dipiperidinyl diethoxysilane solution, resulting in varying degrees of ink accumulation and ink deterioration at the edges of the screen printing plate.

[0201] Compared with Example 8, Comparative Examples 14-15 changed the composition of the developer, resulting in a decrease in both the developing effect and the developing speed.

[0202] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A color difference control method of a Mini LED PCB, characterized in that: The method comprises the following steps: grinding the modified volcanic ash to a certain granularity, and then mixing the modified volcanic ash with a silane solution to form a modified volcanic ash solution. The preparation method of the modified volcanic ash comprises the following steps: grinding the volcanic ash, acidizing the volcanic ash, then washing the volcanic ash with water, drying the volcanic ash, and then immersing the volcanic ash in a water-soluble cellulose ether water suspension. The water-soluble cellulose ether is one or any combination of carboxymethyl cellulose calcium, cellulose acetate, triacetate cellulose, and ethyl cellulose. The modified volcanic ash solution further comprises a polyhydric alcohol, and the polyhydric alcohol is dipropyl glycerol, glycerol, polyethylene glycol, or glucose.

2. The color difference control method according to claim 1, characterized by: The concentration of the modified volcanic ash solution is 12-20% by mass, and the grinding rate is 1.5-2.5 m / min.

3. The method of claim 1, wherein: The color difference control method further comprises a printing consistency treatment, and the printing consistency treatment comprises the following steps: spraying a silane solution on the edges of a silk screen plate, and then performing anti-welding silk screen printing after drying. The silane is one or any combination of dipiperidyl diethoxysilane, ureidopropyl triethoxysilane, gamma-aminopropyl trimethoxysilane, and gamma-aminopropyl triethoxysilane, and the amount of silane injected is 0.01 to 0.08 g / cm 2 .

4. The method of claim 1, wherein: The water-soluble cellulose ether is carboxymethyl cellulose calcium.

5. The method of claim 1, wherein: The polyhydric alcohol is dipropyl glycerol.

6. The method of claim 3, wherein: The silane is dipiperidyl diethoxysilane.

7. A cleaning process for use in the color difference control method of the Mini LED PCB of claim 1, characterized by: After the volcanic ash grinding plate consistency treatment, the PCB substrate is cleaned, and the cleaning steps comprise the following steps: first, washing with water, then cleaning with an acetic acid aqueous solution at 30-50℃, and then washing with water and drying.

8. The cleaning process of claim 7, wherein: The acetic acid aqueous solution cleaning conditions comprise the following steps: First, clean the PCB substrate with 3-8% acetic acid aqueous solution at a flow rate of 2-5 L / min at 35-45℃ under normal pressure for 10-20 min; Then, clean the PCB substrate with 10-15% acetic acid aqueous solution at a flow rate of 4-6 L / min at 40-50℃ under normal pressure for 15-30 min. Then, at 30-40°C, the surface is cleaned with 2-4% acetic acid aqueous solution at a flow rate of 10-20 L / min for 3-6 min, the pressure being 3-5 kg / cm 3 , the cleaning angle being 30-60°. Finally, at 30-35 °C, the surface is cleaned with 1-3% acetic acid solution at a flow rate of 20-30 L / min for 2-4 min, with a pressure of 5-8 kg / cm 3 and a cleaning angle of 60-80°.

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