Metal surface amphoteric electrodeposition photoresist, and preparation method and application thereof

Abstract

This invention discloses a method for preparing amphoteric electrodeposition photoresist on a metal surface, specifically including the following steps: Step 1, synthesizing cashew nut shellac monomer; Step 2, preparing an amphoteric resin; Step 3, preparing an electrophoretic coating; Step 4, electrophoretically depositing photoresist on a conductive substrate. This invention also discloses the preparation method and application of amphoteric electrodeposition photoresist on a metal surface. This invention solves the problems of existing photoresists causing complex formation due to strong alkalis, corrosion of metal circuits by strong acids, and swelling of the photoresist film.

Description

Technical Field

[0001] This invention belongs to the field of photoresist preparation technology, and relates to amphoteric electrodeposition photoresist on metal surfaces. This invention also relates to the preparation method and application of amphoteric electrodeposition photoresist on metal surfaces. Background Technology

[0002] Electrodeposition of photoresist utilizes the principle of electrodeposition. Photoresist applications are based on conductive substrate surfaces. During electrodeposition, if the photoresist has a pH value above 8 (pH>8), which is alkaline, complexes will form. Increased alkalinity leads to more stable copper-ammonia complex ions, significantly shifting the copper deposition potential negatively, increasing cathodic polarization, exacerbating hydrogen evolution side reactions, reducing current efficiency, and inducing anodic passivation. For example, copper metal will form copper-ammonia complexes, and the strength of these complexes increases with increasing alkalinity. Increased alkalinity leads to more stable copper-ammonia complex ions, significantly shifting the copper deposition potential negatively, increasing cathodic polarization, exacerbating hydrogen evolution side reactions, reducing current efficiency, and inducing anodic passivation. At pH values ​​below 4.5 (pH<4.5), strong acids corrode metal circuits, and the acid resistance does not meet the requirements for precision circuit applications. Therefore, proposing a weakly alkaline or weakly acidic electrodeposition photoresist can solve the key technical problems existing in the industry (the formation of complexes during electrodeposition under strong alkaline conditions and the corrosion of metal circuits by strong acids). In addition, electrophoresis is carried out in an aqueous solution. After electrophoresis, a photoresist film is formed on the surface of a conductive metal. If the hydrophobicity of the film is poor, it will cause the film to swell, resulting in poor subsequent photolithography effect. Summary of the Invention

[0003] The purpose of this invention is to provide an amphoteric electrodeposition photoresist for metal surfaces, which solves the problems of existing photoresists causing complex formation due to strong alkali, corrosion of metal circuits by strong acid, and swelling of the photoresist film.

[0004] A second objective of this invention is to provide a method for preparing amphoteric electrodeposition photoresist on metal surfaces.

[0005] A third objective of this invention is to provide applications of amphoteric electrodeposition photoresists on metal surfaces.

[0006] The first technical solution adopted in this invention is a method for preparing amphoteric electrodeposition photoresist on a metal surface, specifically including the following steps: Step 1: Synthesize cashew phenol monomer; Step 2: Prepare amphoteric resin; Step 3, prepare electrophoretic paint; Step 4: Electrophoretically deposit photoresist on the conductive substrate.

[0007] The first technical solution of this invention is further characterized by: The specific process of step 1 is as follows: Cashew phenol is added to N,N-dimethylformamide solution, then sodium hydroxide is added, and the mixture is stirred at room temperature for 30-60 minutes. Then 4-vinylbenzyl chloride is added, and the mixture is stirred at room temperature for 5-8 hours. After the reaction is completed, CH2Cl2 and deionized water are added to the reaction solution. After extraction, the mixture is separated and the organic phase is collected. This process is repeated three times. The solvent is removed by rotary evaporation of the final organic phase to obtain cashew phenol monomer.

[0008] The specific process of step 2 is as follows: Step 2.1: Take methacrylic acid, dimethylaminoethyl methacrylate and solvent, stir at room temperature for 10-20 minutes to obtain a homogeneous ionic monomer, and pour the ionic monomer into constant pressure dropping funnel I; Step 2.2: Take cashew phenol monomer, butyl acrylate, methyl methacrylate, hydroxyethyl acrylate, styrene and azobisisobutyronitrile, stir evenly to obtain a mixed solution, and pour the mixed solution into constant pressure dropping funnel II; Step 2.3: Take a three-necked flask, fill it with nitrogen gas, and place constant-pressure dropping funnel I and constant-pressure dropping funnel II on opposite sides of the flask, setting the reaction temperature to 65-75°C. o C. Start stirring, then start adding liquid in constant pressure dropping funnel I and constant pressure dropping funnel II at the same dropping rate for 1-2 hours. After the addition is complete, continue stirring for 1-2 hours. When the viscosity reaches 5000-15000 cps, stop heating and add hydroquinone to terminate the reaction. Step 2.4: Add acrylic anhydride to the solution obtained in Step 2.3 and heat to 50-100°C. o C. React for 10-60 minutes. After the reaction is complete, add solvent to dilute and obtain the amphoteric resin.

[0009] In step 3, the electrophoretic paint is either acid-neutralized electrophoretic paint or alkali-neutralized electrophoretic paint.

[0010] In step 3, the preparation process of the acid-neutralized electrophoretic paint is as follows: Add the acidic substance to deionized water to obtain an acidic solution. Gradually add the acidic solution dropwise to the amphoteric resin. Stop adding the acidic solution when the pH reaches 4.5-6.5. Continue to add deionized water to dilute the resin to a solid content of 0.1-20%. Then add a photoinitiator to obtain the acid-neutralized electrophoretic paint.

[0011] The preparation process of alkali-neutralized electrophoretic paint is as follows: Add an alkaline substance to deionized water to obtain an alkaline solution; then gradually add the alkaline solution dropwise to the amphoteric resin. Stop adding the alkaline solution when the pH reaches 7.5-9.2, continue adding deionized water to dilute the resin to a solid content of 0.1-20%, and then add a photoinitiator to obtain the alkali-neutralized electrophoretic paint.

[0012] Step 5 is as follows: The electrophoretic paint is poured into an electrophoretic pool. Two conductive substrates are inserted into both sides of the pool. A voltage of 20V-200V is then applied for electrophoresis. The electrophoretic paint will deposit as a film on the conductive metal. Once the film thickness reaches 1µm-45µm, the power is turned off, and the electrophoretically deposited conductive substrate is placed in an oven at 45-150°C. o Baking at C for 1-2 hours yields a conductive substrate with photoresist deposited on it.

[0013] In step 5, the conductive metal is one of copper, nickel, aluminum, silver, gold, titanium, and palladium, and the substrate is polyimide, polyetherimide, glass fiber, polyethylene terephthalate, or blank.

[0014] The second technical solution adopted in this invention is a metal surface amphoteric electrodeposition photoresist, which is prepared by a metal surface amphoteric electrodeposition photoresist preparation method.

[0015] The third technical solution adopted in this invention is the application of amphoteric electrodeposition photoresist on metal surfaces in metal etching.

[0016] The beneficial effects of this invention are as follows: This invention constructs an amphoteric resin that not only achieves weak acid neutralization (pH>4.5) and weak alkaline neutralization (pH<8), but also allows for the simultaneous production of both acidic and alkaline electrophoretic paints. Simultaneously, the introduction of cashew phenol monomers improves the hydrophobicity of the film, thereby enhancing the photolithography effect. Compared to traditional coating and spin-coating photoresists (which can only be applied to simple shapes such as planar surfaces), electrodeposited photoresists can be applied to irregular structures (three-dimensional), forming stepped patterns and other features on these structures after photolithography. Attached Figure Description

[0017] Figure 1 This invention relates to the preparation method of amphoteric electrodeposition photoresist on metal surfaces, and electrophoretic deposition patterns of acid-neutralized electrophoretic paint or alkali-neutralized electrophoretic paint on conductive substrates. Figure 2 This is a flowchart of the photolithography process for preparing amphoteric electrodeposition photoresist on a conductive substrate surface using the method of preparing amphoteric electrodeposition photoresist on a metal surface according to the present invention. Figure 3 This is a photolithography effect diagram of the electrophoretic photoresist in Example 1 of the preparation method of the amphoteric electrodeposition photoresist on the metal surface of the present invention; Figure 4 This is a simplified schematic diagram of the mask photolithography process in the irregular structure in Example 4 of the preparation method of the amphoteric electrodeposition photoresist on the metal surface of the present invention. Figure 5 This is a photolithography effect diagram of the electrophoretic photoresist in Example 4 of the preparation method of the amphoteric electrodeposition photoresist on the metal surface of the present invention; Figure 6This is a photolithography effect diagram of the electrophoretic photoresist in Comparative Example 1, which is a method for preparing amphoteric electrodeposition photoresist on metal surfaces according to the present invention. Figure 7 This is a comparative example 4, showing the photolithography effect of the electrophoretic photoresist in the preparation method of the amphoteric electrodeposition photoresist on the metal surface of the present invention. Detailed Implementation

[0018] The following detailed description is provided in conjunction with specific implementation methods.

[0019] The method for preparing amphoteric electrodeposition photoresist on a metal surface according to the present invention specifically includes the following steps: Step 1, the synthesis of cashew nut shellac monomer, the specific process is as follows: Add 30-60 g of cashew nut shell phenol (C15:1) to 50-100 mL of N,N-dimethylformamide (DMF) solution, then add 4.2-8.4 g of sodium hydroxide. Stir at room temperature for 30-60 minutes, then add 15.3-30.6 g of 4-vinylbenzyl chloride. Stir at room temperature for 5-8 hours. After the reaction is complete, add 100-200 mL of CH2Cl2 and 200-400 mL of deionized water to the reaction solution. Extract and separate the liquid, collecting the organic phase. Repeat this process three times. Remove the solvent from the final organic phase by rotary evaporation to obtain the cashew nut shell phenol monomer in 95-98% yield.

[0020] Step 2, preparation of the amphoteric resin, the specific process is as follows: Step 2.1: Take 22-44g of methacrylic acid, 30-60g of dimethylaminoethyl methacrylate and 91-182mL of solvent (one of ethylene glycol butyl ether, isopropanol, n-butanol, and benzyl alcohol), stir at room temperature for 10-20 minutes to obtain a homogeneous ionic monomer. Pour the ionic monomer into constant pressure dropping funnel I for later use.

[0021] Step 2.2: Take 35-70g of cashew phenol monomer, 15-30g of butyl propylene glycol, 56-112g of methyl methacrylate, 22-44g of hydroxyethyl acrylate, 15-30g of styrene, and 50-100mg of azobisisobutyronitrile, stir well to obtain a mixed solution, and pour it into constant pressure dropping funnel II for later use. Step 2.3: Take a 250-500 mL three-necked flask, fill it with nitrogen, and place constant pressure dropping funnel I and constant pressure dropping funnel II on opposite sides of the three-necked flask, setting the reaction time to 65-75 °C. o C. Start stirring, then start adding liquid in constant pressure dropping funnel I and constant pressure dropping funnel II at the same dropping rate for 1-2 hours. After the addition is complete, continue stirring for 1-2 hours. When the viscosity reaches 5000-15000 cps, stop heating and add 120-240 mg of hydroquinone to terminate the reaction. Step 2.4: Add 12.6-25.2 g of acrylic anhydride to the solution obtained in Step 2.3, and heat to 50-100°C. o C. React for 10-60 minutes. After the reaction is complete, add 200-400 mL of solvent (one of ethylene glycol butyl ether, isopropanol, n-butanol, or benzyl alcohol) to dilute and obtain the amphoteric resin.

[0022] Step 3, preparation of acid-neutralized electrophoretic paint, is as follows: Take 1-2g of an acidic substance (one of lactic acid, formic acid, acetic acid, benzoic acid, ethyl acetate, or acrylic acid) and add it to 5-10mL of deionized water to obtain an acidic solution. Gradually add the acidic solution dropwise to 10-20g of amphoteric resin. Stop adding the acidic solution when the pH reaches 4.5-6.5. Continue to add deionized water to dilute the resin to a solid content of 0.1-20%. Then add 50-500mg of photoinitiator (photoinitiator 1173, (2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone) or oligomer-type α-hydroxy ketone Chivacure® 70) to obtain an acid-neutralized electrophoretic paint.

[0023] Step 4, preparation of alkali-neutralized electrophoretic paint, is as follows: Take 1-2g of an alkaline substance (one of triethylamine, pyridine, 4-methylpyridine, or pyrrole) and add it to 5-10mL of deionized water to obtain an alkaline solution. Then, gradually add the alkaline solution to 10-20g of amphoteric resin. Stop adding the alkaline solution when the pH reaches 7.5-8 (9.2). Continue to add deionized water to dilute the resin to 0.1-20% solid content. Then add 50-500mg of photoinitiator (photoinitiator 1173, (2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone) or oligomer-type α-hydroxy ketone Chivacure® 70) to obtain an alkaline-neutralized electrophoretic paint.

[0024] Step 5: Electrophoretic deposition of photoresist on the conductive substrate. The specific process is as follows: like Figure 1 As shown, the electrophoretic coating pool is filled with acid-neutralized or alkali-neutralized electrophoretic coating. Two conductive substrates (the conductive metal layer can be copper, nickel, aluminum, silver, gold, titanium, palladium, etc., and the substrate can be polyimide, polyetherimide, glass fiber, polyethylene terephthalate, or blank, etc.) are inserted into opposite sides of the electrophoretic coating pool. Then, a voltage of 20V-200V is applied for electrophoresis, and the electrophoretic coating will deposit into a film on the conductive metal. When the film thickness reaches 1µm-45µm, the power is turned off, and the electrophoretically deposited conductive substrate is placed in an oven at 45-150°C. o Baking at C for 1-2 hours yields a conductive substrate with photoresist deposited on it.

[0025] Etching process: such as Figure 2 As shown, the photolithography process involves placing a conductive substrate under a mask (blank stripe width 3.99-6.3um; masked stripe width 7.66-9.13um), and then irradiating it with ultraviolet-visible light at wavelengths such as ArF (193nm), KrF (248nm), g-line (405nm-436nm), and i-line (365nm-385nm-395nm), with light energy ranging from 50mJ to 3000mJ. The exposed areas form a hard film, while the masked areas, i.e., the unexposed areas, are stripped using an alkaline developer (potassium hydroxide aqueous solution, tetramethylammonium hydroxide (TMAH) aqueous solution, and amine-based developer) to expose the metal layer. The exposed metal is then further etched away using an etching solution (iodine-potassium iodide (KI-I2) solution, a mixture of phosphoric acid / acetic acid / nitric acid, and a mixture of cerium ammonium nitrate / acetic acid). Finally, the hard film is washed away using a mixed solvent of ethylene glycol butyl ether and isopropanol (100-200 mL, v:v=1:1, sodium hydroxide, potassium hydroxide, and a special alkaline stripping solution).

[0026] Example 1 Step 1, the synthesis of cashew nut shellac monomer, the specific process is as follows: 30 g of cashew nut shellac (C15:1) was added to 50 mL of N,N-dimethylformamide (DMF) solution, followed by 4.2 g of sodium hydroxide. The mixture was stirred at room temperature for 30 minutes. Then, 15.3 g of 4-vinylbenzyl chloride was added, and the mixture was stirred at room temperature for 5 hours. After the reaction was complete, 100 mL of CH2Cl2 and 200 mL of deionized water were added to the reaction mixture. The mixture was extracted, separated, and the organic phase was collected. This process was repeated three times. The solvent was removed from the final organic phase by rotary evaporation to obtain the cashew nut shellac monomer in 95% yield.

[0027] Step 2, preparation of the amphoteric resin, the specific process is as follows: Step 2.1: Take 22g of methacrylic acid, 30g of dimethylaminoethyl methacrylate and 91mL of ethylene glycol butyl ether, stir at room temperature for 10 minutes to obtain a homogeneous ionic monomer, pour it into constant pressure dropping funnel I, and set aside.

[0028] Step 2.2: Take 35g of cashew phenol monomer, 15g of butyl propylene glycol, 56g of methyl methacrylate, 22g of hydroxyethyl acrylate, 15g of styrene, and 50mg of azobisisobutyronitrile, stir them evenly to obtain a mixed solution, and pour it into constant pressure dropping funnel II for later use.

[0029] Step 2.3: Take a 250mL three-necked flask, fill it with nitrogen gas, and place constant-pressure dropping funnel I and constant-pressure dropping funnel II on opposite sides of the three-necked flask, setting the reaction temperature to 65°C. oC. Start stirring, then begin adding the solution dropwise using constant pressure dropping funnel I and constant pressure dropping funnel II at equal rates for 1 hour. After the addition is complete, continue stirring for 1 hour. When the viscosity reaches 5000-15000 cps, stop heating and add 120 mg of hydroquinone to terminate the reaction.

[0030] Step 2.4: Add 12.6g of acrylic anhydride to the terminated solution and heat to 50°C. o C. React for 10 minutes. After the reaction is complete, add 200 mL of solvent (ethylene glycol butyl ether) to dilute and obtain the amphoteric resin.

[0031] Step 3, preparation of acid-neutralized electrophoretic paint, is as follows: Take 1g of acidic substance (lactic acid) and add it to 5mL of deionized water. Then, gradually add the lactic acid solution to 10g of amphoteric resin. Stop adding the lactic acid solution when the pH reaches 4.5. Continue to add deionized water to dilute the resin to 0.1% solid content. Then add 500mg of photoinitiator 1173 to obtain acid-neutralized electrophoretic paint.

[0032] Step 4: Electrophoretic deposition of photoresist on the conductive substrate, as detailed below: like Figure 1 As shown, the electrophoretic coating cell is filled with acid-neutralized electrophoretic paint. Two conductive substrates (copper conductive metal layer, polyimide substrate) are inserted into opposite sides of the electrophoretic cell. Electrophoresis is then performed with a voltage of 20V-200V until the film thickness reaches 1µm, at which point the power is turned off. The electrophoretically deposited conductive substrate is then placed in an oven at 45°C. o Bake at C for 1 hour.

[0033] Etching process like Figure 2 As shown, the photolithography process involves placing a conductive substrate under a mask and irradiating it with ultraviolet-visible light at a wavelength of ArF (193nm) with an energy of 50mJ-100mJ. The exposed areas form a hard film, while the masked areas (unexposed regions) are stripped using an alkaline developer (potassium hydroxide aqueous solution) to expose the metal layer. Further etching is performed using an etchant (iodine-potassium iodide (KI-I2) solution) to remove the exposed metal. Finally, the hard film is washed away using a mixed solvent of ethylene glycol butyl ether and isopropanol (100mL, v:v=1:1).

[0034] Example 2 Step 1, the synthesis of cashew nut shellac monomer, the specific process is as follows: 60 g of cashew nut shellac (C15:1) was added to 100 mL of N,N-dimethylformamide (DMF) solution, followed by 8.4 g of sodium hydroxide. The mixture was stirred at room temperature for 60 minutes. Then, 30.6 g of 4-vinylbenzyl chloride was added, and the mixture was stirred at room temperature for 8 hours. After the reaction was complete, 200 mL of CH2Cl2 and 400 mL of deionized water were added to the reaction mixture. The mixture was extracted, separated, and the organic phase was collected. This process was repeated three times. The solvent was removed from the final organic phase by rotary evaporation to obtain the cashew nut shellac monomer in 98% yield.

[0035] Step 2, preparation of the amphoteric resin, the specific process is as follows: Step 2.1: Take 44g of methacrylic acid, 60g of dimethylaminoethyl methacrylate and 182mL of n-butanol, stir at room temperature for 20 minutes to obtain a homogeneous ionic monomer, pour it into constant pressure dropping funnel I, and set aside.

[0036] Step 2.2: Take 70g of cashew phenol monomer, 30g of butyl acrylate, 112g of methyl methacrylate, 44g of hydroxyethyl acrylate, 30g of styrene and 100mg of azobisisobutyronitrile, stir well to obtain a mixed solution, and pour it into constant pressure dropping funnel II for later use.

[0037] Step 2.3: Take a 500mL three-necked flask, fill it with nitrogen gas, and place constant pressure dropping funnel I and constant pressure dropping funnel II on opposite sides of the three-necked flask, respectively. Set the reaction temperature to 75°C. o C. Start stirring, then begin adding the solution dropwise using constant pressure dropping funnel I and constant pressure dropping funnel II at equal rates for 2 hours. After the addition is complete, continue stirring for another 2 hours. When the viscosity reaches 5000-15000 cps, stop heating and add 240 mg of hydroquinone to terminate the reaction.

[0038] Step 2.4: Add 25.2g of acrylic anhydride to the terminated solution and heat to 100°C. o C. React for 60 minutes. After the reaction is complete, add 400 mL of solvent (one of the benzyl alcohols) to dilute and obtain the amphoteric resin.

[0039] Step 3, preparation of acid-neutralized electrophoretic paint, is as follows: Add 2g of alkaline substance (pyrrole) to 10mL of deionized water, then gradually add the alkaline solution dropwise to 20g of amphoteric resin. Stop adding the alkaline solution when the pH reaches 8, and continue adding deionized water to dilute the resin solid content to 20%. Then add 500mg of photoinitiator, α-hydroxy ketone Chivacure® 70, which is a photoinitiator oligomer.

[0040] Step 4: Electrophoretic deposition of photoresist on the conductive substrate. The specific process is as follows: like Figure 1 As shown, the electrophoretic coating pool is filled with alkali-neutralized electrophoretic paint. Two conductive substrates (with palladium as the conductive metal layer and polyethylene terephthalate as the substrate) are inserted into opposite sides of the electrophoretic coating pool. Electrophoresis is then performed with a voltage of 200V until the film thickness reaches 45µm, at which point the power is turned off. The electrophoretically deposited conductive substrate is then placed in an oven at 150°C. o Bake at C for 2 hours.

[0041] Etching process: such as Figure 2 As shown, the photolithography process involves placing a conductive substrate under a mask and irradiating it with ultraviolet-visible light at a wavelength of 365nm (i-line) with an energy of 3000mJ. The exposed areas form a hard film, while the masked areas (unexposed regions) are stripped using an alkaline developer (tetramethylammonium hydroxide (TMAH) aqueous solution) to expose the metal layer. Further etching is performed using an etching solution (a mixture of cerium ammonium nitrate and acetic acid) to remove the exposed metal. Finally, the hard film is washed away using a mixed solvent of ethylene glycol butyl ether and isopropanol (200 mL, v:v = 1:1).

[0042] Example 3 Step 1, the synthesis of cashew nut shellac monomer, the specific process is as follows: 45 g of cashew nut shellac (C15:1) was added to 75 mL of N,N-dimethylformamide (DMF) solution, followed by 6.3 g of sodium hydroxide. The mixture was stirred at room temperature for 45 minutes. Then, 22.95 g of 4-vinylbenzyl chloride was added, and the mixture was stirred at room temperature for 6.5 hours. After the reaction was complete, 150 mL of CH2Cl2 and 300 mL of deionized water were added to the reaction mixture. The mixture was extracted, separated, and the organic phase was collected. This process was repeated three times. The solvent was removed from the final organic phase by rotary evaporation to obtain the cashew nut shellac monomer in 97% yield.

[0043] Step 2, preparation of the amphoteric resin, the specific process is as follows: Step 2.1: Take 33g of methacrylic acid, 45g of dimethylaminoethyl methacrylate and 136.5mL of isopropanol, stir at room temperature for 15 minutes to obtain a homogeneous ionic monomer, pour it into constant pressure dropping funnel I, and set aside.

[0044] Step 2.2: Take 55g of cashew phenol monomer, 22.5g of butyl propylene glycol, 56-112g of methyl methacrylate, 22-44g of hydroxyethyl acrylate, 15-30g of styrene, and 84mg of azobisisobutyronitrile, stir well to obtain a mixed solution, and pour it into constant pressure dropping funnel II for later use.

[0045] Step 2.3: Take a 375 mL three-necked flask, fill it with nitrogen gas, and place constant pressure dropping funnel I and constant pressure dropping funnel II on opposite sides of the three-necked flask, setting the reaction temperature to 70 °C.o C. Start stirring, then begin adding the solution dropwise using constant pressure dropping funnel I and constant pressure dropping funnel II at equal rates for 1.5 hours. After the addition is complete, continue stirring for another 1.5 hours. When the viscosity reaches 5000-15000 cps, stop heating and add 180 mg of hydroquinone to terminate the reaction.

[0046] Step 2.4: Add 18.9g of acrylic anhydride to the terminated solution and heat to 75°C. o C. React for 35 minutes. After the reaction is complete, add 300 mL of solvent (isopropanol) to dilute and obtain the amphoteric resin.

[0047] Step 3, preparation of alkali-neutralized electrophoretic paint, is as follows: Add 1.5g of alkaline substance (pyridine) to 7.5mL of deionized water, and then gradually add the alkaline solution to 15g of amphoteric resin. Stop adding the alkaline solution when the pH reaches 7.7, and continue to add deionized water to dilute the resin to 10% solid content. Then add 300mg of photoinitiator (2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone).

[0048] Step 4: Electrophoretic deposition of photoresist on the conductive substrate. The specific process is as follows: like Figure 1 As shown, the electrophoretic coating pool is filled with alkali-neutralized electrophoretic paint. Two conductive substrates (aluminum as the conductive metal layer and polyetherimide as the substrate) are inserted into opposite sides of the electrophoretic pool. Electrophoresis is then performed with a voltage of 100V until the film thickness reaches 25µm, at which point the power is turned off. The electrophoretically deposited conductive substrate is then placed in an oven at 100°C. o Bake at 1.5°C for 1.5 hours.

[0049] Etching process: such as Figure 2 As shown, the photolithography process involves placing a conductive substrate under a mask and irradiating it with ultraviolet-visible light at a wavelength of KrF (248 nm) with an energy of 2000 mJ. The exposed areas form a hard film, while the masked areas (unexposed regions) are stripped using an alkaline developer (potassium hydroxide aqueous solution 1) to expose the metal layer. Further etching is performed using an etching solution (a mixture of 1-phosphoric acid / acetic acid / nitric acid 1) to remove the exposed metal. Finally, the hard film is washed away using a mixed solvent of ethylene glycol butyl ether and isopropanol (150 mL, v:v = 1:1).

[0050] Example 4 (Replacing the two-dimensional planar conductive substrate with an anisotropic conductive substrate and replacing the mask, a three-dimensional structure corresponding to the mask can be obtained by electrodeposition photolithography) Step 1, the synthesis of cashew nut shellac monomer, the specific process is as follows: 30 g of cashew nut shellac (C15:1) was added to 50 mL of N,N-dimethylformamide (DMF) solution, followed by 4.2 g of sodium hydroxide. The mixture was stirred at room temperature for 30 minutes. Then, 15.3 g of 4-vinylbenzyl chloride was added, and the mixture was stirred at room temperature for 5 hours. After the reaction was complete, 100 mL of CH2Cl2 and 200 mL of deionized water were added to the reaction mixture. The mixture was extracted, separated, and the organic phase was collected. This process was repeated three times. The solvent was removed from the final organic phase by rotary evaporation to obtain the cashew nut shellac monomer in 95% yield.

[0051] Step 2, preparation of the amphoteric resin, the specific process is as follows: Step 2.1: Take 22g of methacrylic acid, 30g of dimethylaminoethyl methacrylate and 91mL of (ethylene glycol butyl ether), stir at room temperature for 10 minutes to obtain a homogeneous ionic monomer, pour it into constant pressure dropping funnel I, and set aside.

[0052] Step 2.2: Take 35g of cashew phenol monomer, 15g of butyl propylene glycol, 56g of methyl methacrylate, 22g of hydroxyethyl acrylate, 15g of styrene, and 50mg of azobisisobutyronitrile, stir them evenly to obtain a mixed solution, and pour it into constant pressure dropping funnel II for later use.

[0053] Step 2.3: Take a 250mL three-necked flask, fill it with nitrogen gas, and place constant-pressure dropping funnel I and constant-pressure dropping funnel II on opposite sides of the three-necked flask, setting the reaction temperature to 65°C. o C. Start stirring, then begin adding the solution dropwise using constant pressure dropping funnel I and constant pressure dropping funnel II at equal rates for 1 hour. After the addition is complete, continue stirring for 1 hour. When the viscosity reaches 5000-15000 cps, stop heating and add 120 mg of hydroquinone to terminate the reaction.

[0054] Step 2.4: Add 12.6g of acrylic anhydride to the terminated solution and heat to 50°C. o C. React for 10 minutes. After the reaction is complete, add 200 mL of solvent (ethylene glycol butyl ether) to dilute.

[0055] Step 3, preparation of acid-neutralized electrophoretic paint, is as follows: Take 1g of acidic substance (lactic acid) and add it to 5mL of deionized water. Then, gradually add the lactic acid solution dropwise to 10g of amphoteric resin. Stop adding the lactic acid solution when the pH reaches 4.5. Continue to add deionized water to dilute the resin to a solid content of 0.1%. Then, add 500mg of photoinitiator 1173 to obtain the amphoteric resin.

[0056] Step 4: Electrophoretic deposition of photoresist on the conductive substrate, as detailed below: like Figure 1As shown, the electrophoretic coating cell is filled with acid-neutralized electrophoretic paint. Two conductive substrates with different structures (copper conductive metal layer and polyimide substrate) are inserted into opposite sides of the electrophoretic cell. Electrophoresis is then performed using a voltage of 20V-200V. Once the film thickness reaches 1µm, the power is turned off. The electrophoretically deposited conductive substrate is then placed in an oven at 45°C. o Bake at C for 1 hour.

[0057] Etching process: such as Figure 2 As shown, the photolithography process involves placing a conductive substrate under a mask and irradiating it with ultraviolet-visible light at a wavelength of ArF (193nm) with an energy of 50mJ-100mJ. The exposed areas form a hard film, while the masked areas (unexposed regions) are stripped using an alkaline developer (potassium hydroxide aqueous solution) to expose the metal layer. Further etching is then performed using an etchant (iodine-potassium iodide (KI-I2) solution) to remove the exposed metal.

[0058] Comparative Example 1 (Dimethylaminoethyl methacrylate, methacrylic acid, and all other monomers were mixed evenly and then subjected to free radical polymerization, with slightly poorer results (corresponding to step 2.1)) Step 1, the synthesis of cashew nut shellac monomer, the specific process is as follows: 30 g of cashew nut shellac (C15:1) was added to 50 mL of N,N-dimethylformamide (DMF) solution, followed by 4.2 g of sodium hydroxide. The mixture was stirred at room temperature for 30 minutes. Then, 15.3 g of 4-vinylbenzyl chloride was added, and the mixture was stirred at room temperature for 5 hours. After the reaction was complete, 100 mL of CH2Cl2 and 200 mL of deionized water were added to the reaction mixture. The mixture was extracted, separated, and the organic phase was collected. This process was repeated three times. The solvent was removed from the final organic phase by rotary evaporation to obtain the cashew nut shellac monomer in 95% yield.

[0059] Step 2, preparation of the amphoteric resin, the specific process is as follows: Step 2.1: Take 22g of methacrylic acid, 30g of dimethylaminoethyl methacrylate and 91mL of ethylene glycol butyl ether, 35g of cashew nut shell powder monomer, 15g of butyl acrylate, 56g of methyl methacrylate, 22g of hydroxyethyl acrylate, 15g of styrene and 50mg of azobisisobutyronitrile, stir well to obtain a mixed solution, pour it into constant pressure dropping funnel I, and set aside.

[0060] Step 2.2: Take a 250mL two-necked flask, fill it with nitrogen gas, and place the constant pressure dropping funnel I to the side of the two-necked flask. Set the reaction temperature to 65°C. o C. Start stirring, then begin adding the solution dropwise using constant pressure dropping funnel I over a period of 1 hour. After the addition is complete, continue stirring for another 1 hour. When the viscosity reaches 5000-15000 cps, stop heating and add 120 mg of hydroquinone to terminate the reaction.

[0061] Step 2.3: Add 12.6g of acrylic anhydride to the terminated solution and heat to 50°C. o C. React for 10 minutes. After the reaction is complete, add 200 mL of solvent (ethylene glycol butyl ether) to dilute.

[0062] Step 3, preparation of acid-neutralized electrophoretic paint, is as follows: Add 1g of acidic substance (lactic acid) to 5mL of deionized water. Then, gradually add the lactic acid solution dropwise to 10g of amphoteric resin. Stop adding the lactic acid solution when the pH reaches 4.5. Continue adding deionized water to dilute the resin to a solid content of 0.1%. Then, add 500mg of photoinitiator 1173 to obtain the acid-neutralized electrophoretic paint.

[0063] Step 4: Electrophoretic deposition of photoresist on the conductive substrate, as detailed below: like Figure 1 As shown, the electrophoretic coating cell is filled with acid-neutralized electrophoretic paint. Two conductive substrates (copper conductive metal layer, polyimide substrate) are inserted into opposite sides of the electrophoretic cell. A voltage of 20V is then applied for electrophoresis. Once the film thickness reaches 1µm, the power is turned off. The electrophoretically deposited conductive substrate is then placed in an oven at 45°C. o Bake at C for 1 hour.

[0064] Etching process: such as Figure 2 As shown, the photolithography process involves placing a conductive substrate under a mask and irradiating it with ultraviolet-visible light at a wavelength of ArF (193nm) with an energy of 50mJ. The exposed areas form a hard film, while the masked areas (unexposed regions) are stripped using an alkaline developer (potassium hydroxide aqueous solution) to expose the metal layer. Further etching is performed using an etchant (iodine-potassium iodide (KI-I2) solution) to remove the exposed metal. Finally, the hard film is washed away using a mixed solvent of ethylene glycol butyl ether and isopropanol (100mL, v:v=1:1).

[0065] Comparative Example 2 (Methacrylic acid solution was added dropwise to dimethylaminoethyl methacrylate solution while polymerization was carried out (compared to steps 2 and 3), the distance between dimethylaminoethyl methacrylate and methacrylic acid was increased, resulting in poorer performance) Step 1, the synthesis of cashew nut shellac monomer, the specific process is as follows: 30 g of cashew nut shellac (C15:1) was added to 50 mL of N,N-dimethylformamide (DMF) solution, followed by 4.2 g of sodium hydroxide. The mixture was stirred at room temperature for 30 minutes. Then, 15.3 g of 4-vinylbenzyl chloride was added, and the mixture was stirred at room temperature for 5 hours. After the reaction was complete, 100 mL of CH2Cl2 and 200 mL of deionized water were added to the reaction mixture. The mixture was extracted, separated, and the organic phase was collected. This process was repeated three times. The solvent was removed from the final organic phase by rotary evaporation to obtain the cashew nut shellac monomer in 95% yield.

[0066] Step 2, preparation of the amphoteric resin, the specific process is as follows: Step 2.1: Take 30g of dimethylaminoethyl methacrylate and 91mL of ethylene glycol butyl ether, stir at room temperature for 10 minutes to obtain a homogeneous ionic monomer, pour it into a 250mL double-necked flask, fill it with nitrogen gas, and set aside for later use.

[0067] Step 2.2: Take 22g of methacrylic acid, 35g of cashew nut shell monomer, 15g of butyl propylene glycol, 56g of methyl methacrylate, 22g of hydroxyethyl acrylate, 15g of styrene, and 50mg of azobisisobutyronitrile, stir them evenly to obtain a mixed solution, and pour it into constant pressure dropping funnel I for later use.

[0068] Step 2.3: Place the constant pressure dropping funnel I on the side of the double-necked flask and set the reaction temperature to 65°C. o C. Start stirring, then begin adding the solution dropwise using constant pressure dropping funnel I over a period of 1 hour. After the addition is complete, continue stirring for another 1 hour. When the viscosity reaches 5000-15000 cps, stop heating and add 120 mg of hydroquinone to terminate the reaction.

[0069] Step 2.4: Add 12.6g of acrylic anhydride to the terminated solution and heat to 50°C. o C. React for 10 minutes. After the reaction is complete, add 200 mL of solvent (ethylene glycol butyl ether) to dilute and obtain the amphoteric resin.

[0070] Step 3, preparation of acid-neutralized electrophoretic paint, is as follows: Add 1g of acidic substance (lactic acid) to 5mL of deionized water. Then, gradually add the lactic acid solution dropwise to 10g of amphoteric resin. Stop adding the lactic acid solution when the pH reaches 4.5. Continue adding deionized water to dilute the resin to a solid content of 0.1%. Then, add 500mg of photoinitiator 1173 to obtain the acid-neutralized electrophoretic paint.

[0071] Step 4: Electrophoretic deposition of photoresist on the conductive substrate, as detailed below: like Figure 1As shown, the electrophoretic coating cell is filled with acid-neutralized electrophoretic paint. Two conductive substrates (copper conductive metal layer, polyimide substrate) are inserted into opposite sides of the electrophoretic cell. A voltage of 20V is then applied for electrophoresis. Once the film thickness reaches 1µm, the power is turned off. The electrophoretically deposited conductive substrate is then placed in an oven at 45°C. o Bake at C for 1 hour.

[0072] Etching process: such as Figure 2 As shown, the photolithography process involves placing a conductive substrate under a mask and irradiating it with ultraviolet-visible light at a wavelength of ArF (193nm) with an energy of 50mJ. The exposed areas form a hard film, while the masked areas (unexposed regions) are stripped using an alkaline developer (potassium hydroxide aqueous solution) to expose the metal layer. Further etching is performed using an etchant (iodine-potassium iodide (KI-I2) solution) to remove the exposed metal. Finally, the hard film is washed away using a mixed solvent of ethylene glycol butyl ether and isopropanol (100mL, v:v=1:1).

[0073] Comparative Example 3 (polymerization of dimethylaminoethyl methacrylate and other monomers (corresponding to step 2.2), polymerization of methacrylic acid and other monomers (corresponding to step 2.1), mixing of basic polymers and acidic polymers (corresponding to step 2.3), the material has poor solubility, produces gel, and is unusable) Step 1, the synthesis of cashew nut shellac monomer, the specific process is as follows: 30 g of cashew nut shellac (C15:1) was added to 50 mL of N,N-dimethylformamide (DMF) solution, followed by 4.2 g of sodium hydroxide. The mixture was stirred at room temperature for 30 minutes. Then, 15.3 g of 4-vinylbenzyl chloride was added, and the mixture was stirred at room temperature for 5 hours. After the reaction was complete, 100 mL of CH2Cl2 and 200 mL of deionized water were added to the reaction mixture. The mixture was extracted, separated, and the organic phase was collected. This process was repeated three times. The solvent was removed from the final organic phase by rotary evaporation to obtain the cashew nut shellac monomer in 95% yield.

[0074] Step 2, preparation of the amphoteric resin, the specific process is as follows: Step 2.1: Take 22g of methacrylic acid, 20g of cashew nut shell monomer, 5g of butyl propylene glycol, 36g of methyl methacrylate, 12g of hydroxyethyl acrylate, 10g of styrene, 25mg of azobisisobutyronitrile, and 91mL of (ethylene glycol butyl ether). Stir at room temperature for 10 minutes, then pour the mixture into constant pressure dropping funnel I. Take a 250mL double-necked flask, fill it with nitrogen, and place constant pressure dropping funnel I on the side of the double-necked flask. Set the reaction temperature to 65°C. oC, and start stirring, then add the solution using a constant pressure dropping funnel I for 1 hour. After the addition is complete, continue stirring for 1 hour. When the viscosity reaches 5000-15000 cps, stop heating and add 120 mg of hydroquinone to terminate the reaction. This is a resin containing methacrylic acid units.

[0075] Step 2.2: Take 30g of dimethylaminoethyl methacrylate, 15g of cashew nut shell powder, 10g of butyl acrylate, 20g of methyl methacrylate, 10g of hydroxyethyl acrylate, 5g of styrene, and 25mg of azobisisobutyronitrile (AIBN), and stir until homogeneous to obtain a mixed solution. Pour this solution into constant pressure dropping funnel II. Take a 250mL double-necked flask, fill it with nitrogen gas, and place constant pressure dropping funnel II on the side of the double-necked flask. Set the reaction time to 65°C. o C. Start stirring, then use constant pressure dropping funnel II to add the solution over 1 hour. After the addition is complete, continue stirring for 1 hour. When the viscosity reaches 5000-15000 cps, stop heating and add 120 mg of hydroquinone to terminate the reaction, obtaining a resin containing dimethylaminoethyl methacrylate.

[0076] In step 2.3, the resin containing methacrylic acid moiety and the resin containing dimethylaminoethyl methacrylate moiety moiety are mixed to form a gel that cannot be dispersed.

[0077] Comparative Example 4 (The lack of cashew phenol monomer in the polymer monomer (corresponding to steps 1.1 and 1.2) resulted in poorer hydrophobicity of the material, larger film swelling ratio, and affected etching efficiency (resolution)) Step 1, preparation of the amphoteric resin, is as follows: Step 1.1: Take 22g of methacrylic acid, 30g of dimethylaminoethyl methacrylate and 91mL of (ethylene glycol butyl ether), stir at room temperature for 10 minutes to obtain a homogeneous ionic monomer, pour it into constant pressure dropping funnel I, and set aside.

[0078] Step 1.2: Take 15g of butyl acrylate, 56g of methyl methacrylate, 22g of hydroxyethyl acrylate, 15g of styrene and 50mg of azobisisobutyronitrile, stir them evenly to obtain a mixed solution, and pour it into constant pressure dropping funnel II for later use.

[0079] Step 1.3: Take a 250mL three-necked flask, fill it with nitrogen gas, and place constant pressure dropping funnel I and constant pressure dropping funnel II on opposite sides of the three-necked flask, setting the reaction temperature to 65°C. o C. Start stirring, then begin adding the solution dropwise using constant pressure dropping funnel I and constant pressure dropping funnel II at equal rates for 1 hour. After the addition is complete, continue stirring for 1 hour. When the viscosity reaches 5000-15000 cps, stop heating and add 120 mg of hydroquinone to terminate the reaction.

[0080] Step 1.4: Add 12.6g of acrylic anhydride to the terminated solution and heat to 50°C. o C. React for 10 minutes. After the reaction is complete, add 200 mL of solvent (ethylene glycol butyl ether) to dilute and obtain the amphoteric resin.

[0081] Step 2, preparation of acid-neutralized electrophoretic paint, is as follows: Add 1g of acidic substance (lactic acid) to 5mL of deionized water. Then, gradually add the lactic acid solution dropwise to 10g of amphoteric resin. Stop adding the lactic acid solution when the pH reaches 4.5. Continue adding deionized water to dilute the resin to a solid content of 0.1%. Then, add 500mg of photoinitiator 1173.

[0082] Step 3: Electrophoretic deposition of photoresist on the conductive substrate, as detailed below: like Figure 1 As shown, the electrophoretic coating cell is filled with acid-neutralized electrophoretic paint. Two conductive substrates (copper conductive metal layer, polyimide substrate) are inserted into opposite sides of the electrophoretic cell. A voltage of 20V is then applied for electrophoresis. Once the film thickness reaches 1µm, the power is turned off. The electrophoretically deposited conductive substrate is then placed in an oven at 45°C. o Bake at C for 1 hour.

[0083] Etching process: such as Figure 2 As shown, the photolithography process involves placing a conductive substrate under a mask and irradiating it with ultraviolet-visible light at a wavelength of ArF (193nm) with an energy of 50mJ. The exposed areas form a hard film, while the masked areas (unexposed regions) are stripped using an alkaline developer (potassium hydroxide aqueous solution) to expose the metal layer. Further etching is performed using an etchant (iodine-potassium iodide (KI-I2) solution) to remove the exposed metal. Finally, the hard film is washed away using a mixed solvent of ethylene glycol butyl ether and isopropanol (100mL, v:v=1:1).

[0084] Comparative Example 5 (without the addition of dimethylaminoethyl methacrylate (corresponding to step 2.1), the polymer chain cannot form salts, and can only be neutralized by amines. However, acid neutralization results in a pH below 4, and water dilution forms a gel, which cannot be dispersed.) Step 1, the synthesis of cashew nut shellac monomer, the specific process is as follows: 30 g of cashew nut shellac (C15:1) was added to 50 mL of N,N-dimethylformamide (DMF) solution, followed by 4.2 g of sodium hydroxide. The mixture was stirred at room temperature for 30 minutes. Then, 15.3 g of 4-vinylbenzyl chloride was added, and the mixture was stirred at room temperature for 5 hours. After the reaction was complete, 100 mL of CH2Cl2 and 200 mL of deionized water were added to the reaction mixture. The mixture was extracted, separated, and the organic phase was collected. This process was repeated three times. The solvent was removed from the final organic phase by rotary evaporation to obtain the cashew nut shellac monomer in 95% yield.

[0085] Step 2, preparation of acidic resin, the specific process is as follows: Step 2.1: Take 22g of methacrylic acid and 91mL of (ethylene glycol butyl ether), stir at room temperature for 10 minutes to obtain a homogeneous ionic monomer, pour it into constant pressure dropping funnel I, and set aside.

[0086] Step 2.2: Take 35g of cashew phenol monomer, 15g of butyl propylene glycol, 56g of methyl methacrylate, 22g of hydroxyethyl acrylate, 15g of styrene, and 50mg of azobisisobutyronitrile, stir them evenly to obtain a mixed solution, and pour it into constant pressure dropping funnel II for later use.

[0087] Step 2.3: Take a 250mL three-necked flask, fill it with nitrogen gas, and place constant-pressure dropping funnel I and constant-pressure dropping funnel II on opposite sides of the three-necked flask, setting the reaction temperature to 65°C. o C. Start stirring, then begin adding the solution dropwise using constant pressure dropping funnel I and constant pressure dropping funnel II at equal rates for 1 hour. After the addition is complete, continue stirring for 1 hour. When the viscosity reaches 5000-15000 cps, stop heating and add 120 mg of hydroquinone to terminate the reaction.

[0088] Step 2.4: Add 12.6g of acrylic anhydride to the terminated solution and heat to 50°C. o C. React for 10 minutes. After the reaction is complete, add 200 mL of solvent (ethylene glycol butyl ether) to dilute and obtain the amphoteric resin.

[0089] Step 3, preparation of acid-neutralized electrophoretic paint, is as follows: The pH of the acidic resin reaches 4.0 directly. If lactic acid solution is added dropwise, the pH will only decrease further. Furthermore, if deionized water is added for dilution, a gel will form that cannot be dispersed.

[0090] Comparative Example 6 (without added methacrylic acid, the polymer chain cannot form salts, resulting in poor solubility (low final solid content), and can only be neutralized by acid) Step 1, the synthesis of cashew nut shellac monomer, the specific process is as follows: 30 g of cashew nut shellac (C15:1) was added to 50 mL of N,N-dimethylformamide (DMF) solution, followed by 4.2 g of sodium hydroxide. The mixture was stirred at room temperature for 30 minutes. Then, 15.3 g of 4-vinylbenzyl chloride was added, and the mixture was stirred at room temperature for 5 hours. After the reaction was complete, 100 mL of CH2Cl2 and 200 mL of deionized water were added to the reaction mixture. The mixture was extracted, separated, and the organic phase was collected. This process was repeated three times. The solvent was removed from the final organic phase by rotary evaporation to obtain the cashew nut shellac monomer in 95% yield.

[0091] Step 2, preparation of alkaline resin, the specific process is as follows: Step 2.1: Take 30g of dimethylaminoethyl methacrylate and 91mL of ethylene glycol butyl ether, stir at room temperature for 10 minutes to obtain a homogeneous ionic monomer, pour it into constant pressure dropping funnel I, and set aside.

[0092] Step 2.2: Take 35g of cashew phenol monomer, 15g of butyl propylene glycol, 56g of methyl methacrylate, 22g of hydroxyethyl acrylate, 15g of styrene, and 50mg of azobisisobutyronitrile, stir them evenly to obtain a mixed solution, and pour it into constant pressure dropping funnel II for later use.

[0093] Step 2.3: Take a 250mL three-necked flask, fill it with nitrogen gas, and place constant-pressure dropping funnel I and constant-pressure dropping funnel II on opposite sides of the three-necked flask, setting the reaction temperature to 65°C. o C. Start stirring, then begin adding the solution dropwise using constant pressure dropping funnel I and constant pressure dropping funnel II at equal rates for 1 hour. After the addition is complete, continue stirring for 1 hour. When the viscosity reaches 5000-15000 cps, stop heating and add 120 mg of hydroquinone to terminate the reaction.

[0094] Step 2.4: Add 12.6g of acrylic anhydride to the terminated solution and heat to 50°C. o C. React for 10 minutes. After the reaction is complete, add 200 mL of solvent (ethylene glycol butyl ether) to dilute and obtain the alkaline resin.

[0095] Step 3, the preparation of amine-neutralized electrophoretic paint, is as follows: The pH of the alkaline resin reaches 8.0 directly. If triethylamine solution is added dropwise, the pH will only decrease further. Furthermore, if deionized water is added for dilution, a gel will form that cannot be dispersed.

[0096] Comparative Example 7 (without added acrylic anhydride, the etching process could not be completed because a hard film could not be formed in the UV irradiation area). Step 1, the synthesis of cashew nut shellac monomer, the specific process is as follows: 30 g of cashew nut shellac (C15:1) was added to 50 mL of N,N-dimethylformamide (DMF) solution, followed by 4.2 g of sodium hydroxide. The mixture was stirred at room temperature for 30 minutes. Then, 15.3 g of 4-vinylbenzyl chloride was added, and the mixture was stirred at room temperature for 5 hours. After the reaction was complete, 100 mL of CH2Cl2 and 200 mL of deionized water were added to the reaction mixture. The mixture was extracted, separated, and the organic phase was collected. This process was repeated three times. The solvent was removed from the final organic phase by rotary evaporation to obtain the cashew nut shellac monomer in 95% yield.

[0097] Step 2, preparation of the amphoteric resin, the specific process is as follows: Step 2.1: Take 22g of methacrylic acid, 30g of dimethylaminoethyl methacrylate and 91mL of (ethylene glycol butyl ether), stir at room temperature for 10 minutes to obtain a homogeneous ionic monomer, pour it into constant pressure dropping funnel I, and set aside.

[0098] Step 2.2: Take 35g of cashew phenol monomer, 15g of butyl propylene glycol, 56g of methyl methacrylate, 22g of hydroxyethyl acrylate, 15g of styrene, and 50mg of azobisisobutyronitrile, stir them evenly to obtain a mixed solution, and pour it into constant pressure dropping funnel II for later use.

[0099] Step 2.3: Take a 250mL three-necked flask, fill it with nitrogen gas, and place constant-pressure dropping funnel I and constant-pressure dropping funnel II on opposite sides of the three-necked flask, setting the reaction temperature to 65°C. o C. Start stirring, then begin adding the solution dropwise using constant-pressure dropping funnel I and constant-pressure dropping funnel II at equal rates for 1 hour. After the addition is complete, continue stirring for 1 hour. When the viscosity reaches 5000-15000 cps, stop heating and add 120 mg of hydroquinone to terminate the reaction. Dilute with 200 mL of solvent (ethylene glycol butyl ether) for later use.

[0100] Step 3, preparation of acid-neutralized electrophoretic paint, is as follows: Add 1g of acidic substance (lactic acid) to 5mL of deionized water, then gradually add the lactic acid solution dropwise to 10g of amphoteric resin. Stop adding the lactic acid solution when the pH reaches 4.5, continue adding deionized water to dilute the resin to 0.1% solid content, and then add 500mg of photoinitiator 1173.

[0101] Step 4: Electrophoretic deposition of photoresist on the conductive substrate, as detailed below: like Figure 1 As shown, the electrophoretic coating cell is filled with acid-neutralized electrophoretic paint. Two conductive substrates (copper conductive metal layer, polyimide substrate) are inserted into opposite sides of the electrophoretic cell. A voltage of 20V is then applied for electrophoresis. Once the film thickness reaches 1µm, the power is turned off. The electrophoretically deposited conductive substrate is then placed in an oven at 45°C.o Bake at C for 1 hour.

[0102] Etching process: such as Figure 2 As shown, the photolithography process involves placing a conductive substrate under a mask and irradiating it with ultraviolet-visible light at a wavelength of ArF (193nm) with an energy of 50mJ. The exposed areas failed to form a hard film, and the alkaline developer (potassium hydroxide aqueous solution) was used for stripping, exposing the entire metal layer. The etching process failed.

[0103] Results Discussion In Example 1, dimethylaminoethyl methacrylate and methacrylic acid first undergo a neutralization reaction to form a homogeneous monomer containing ionic bonds, which is then copolymerized with the remaining monomers. During polymerization, the ionic monomers, in the form of small monomer molecules, directly and uniformly "weave" into adjacent positions of the polymer chain through chain growth. This creates optimal structural conditions for the formation of salts within the polymer chain, resulting in good solubility, high solid content, and the best effect; it can be neutralized by both acids and bases. Figure 3 As shown in the image, the electrophoretic photoresist photolithography effect diagram shows that the electrophoretic photoresist has a very good photolithography effect. The conductive base texture after etching is clearly visible, and a good stepped pattern can be formed after photolithography.

[0104] Example 4 replaces the planar conductive substrate in Example 1 with an irregularly shaped conductive substrate. Using a mask, UV lithography, development, and etching processes are employed to achieve excellent lithography, resulting in a well-formed three-dimensional irregular pattern. Figure 3 In comparison, the masking plate in the irregular structure of Example 4 ( Figure 4 A simplified structural diagram (showing a portion of the mask, not the entire mask) and an image illustrating the electrophoretic photoresist lithography effect. Figure 5 ), Figure 4 and Figure 5 The obvious blue color, rather than the yellow of metallic copper, is mainly due to the fact that the hard film on the surface of the conductive layer (copper) was not removed, and it appears blue under a magnifying glass.

[0105] In Comparative Example 1, after dimethylaminoethyl methacrylate, methacrylic acid, and all other monomers were mixed evenly, the free radical polymers prevented dimethylaminoethyl methacrylate and methacrylic acid from forming ionic salts in close proximity, resulting in poor photolithography and a darker etched pattern. Figure 6 As shown in the figure, the reason is that the etched surface is rough and uneven.

[0106] In Comparative Example 2, a dimethylaminoethyl methacrylate solution was added dropwise to a methacrylic acid solution while polymerization was occurring simultaneously. This controlled increase in the distance between the dimethylaminoethyl methacrylate and methacrylic acid, resulting in a darker etching pattern due to uneven etching surface.

[0107] Comparative Example 3: Dimethylaminoethyl methacrylate and other monomers were polymerized. The methacrylic acid and other monomers were polymerized. The alkaline polymer and the acid-resistant polymer were mixed. The material had poor solubility and produced a gel, making it unusable.

[0108] Comparative Example 4 shows that the lack of cashew phenol monomers in the polymer monomers results in poorer hydrophobicity of the material, a larger film swelling ratio, and affects etching performance and resolution. Figure 7 As shown in the figure, the surface becomes darker and uneven, which may be due to hydrophobic transformation and film swelling during electrophoresis.

[0109] Comparative Example 5, without the addition of dimethylaminoethyl methacrylate, cannot form salts within the polymer chain, resulting in poor solubility; it can only be neutralized by amines.

[0110] Comparative Example 6, without the addition of methacrylic acid, cannot form salts within the polymer chain, resulting in poor solubility (low final solid content) and can only be neutralized by acid.

[0111] Comparative Example 7: Without the addition of acrylic anhydride, the photolithography process could not be completed, and a hard film could not be formed in the UV irradiation area.

[0112] This invention utilizes the design of amphoteric resins to enable the application of a single resin in both acidic and alkaline electrophoretic paints. This improves the cathodic and anodic electrophoretic selectivity of the electrophoretic paint. Furthermore, the introduction of hydrophobic cashew phenol components enhances photolithography performance. Compared to traditional coating and spin-coating photoresists (which can only be applied to simple shapes such as planar surfaces), electrodeposited photoresists can be applied to irregular structures, forming stepped patterns and other features on irregular (three-dimensional) structures after photolithography.

[0113] Example 4 Compared with Example 1, in step 1, 4.2g of sodium hydroxide was added and stirred at room temperature for 45 minutes.

[0114] Example 5 Compared with Example 1, in step 2.1, the mixture was stirred at room temperature for 12 minutes.

[0115] Example 6 Compared to Example 1, in step 2.3, the reaction temperature is set to 68°C.

Claims

1. A method for preparing amphoteric electrodeposition photoresist on a metal surface, characterized in that: Specifically, the steps include the following: Step 1: Synthesize cashew phenol monomer; Step 2: Prepare amphoteric resin; Step 3, prepare electrophoretic paint; Step 4: Electrophoretically deposit photoresist on the conductive substrate.

2. The method for preparing amphoteric electrodeposition photoresist on a metal surface according to claim 1, characterized in that: The specific process of step 1 is as follows: Cashew phenol is added to N,N-dimethylformamide solution, then sodium hydroxide is added, and the mixture is stirred at room temperature for 30-60 minutes. Then 4-vinylbenzyl chloride is added, and the mixture is stirred at room temperature for 5-8 hours. After the reaction is completed, CH2Cl2 and deionized water are added to the reaction solution. After extraction, the mixture is separated and the organic phase is collected. This process is repeated three times. The solvent is removed by rotary evaporation of the final organic phase to obtain cashew phenol monomer.

3. The method for preparing amphoteric electrodeposition photoresist on a metal surface according to claim 1, characterized in that: The specific process of step 2 is as follows: Step 2.1: Take methacrylic acid, dimethylaminoethyl methacrylate and solvent, stir at room temperature for 10-20 minutes to obtain a homogeneous ionic monomer, and pour the ionic monomer into constant pressure dropping funnel I; Step 2.2: Take cashew phenol monomer, butyl acrylate, methyl methacrylate, hydroxyethyl acrylate, styrene and azobisisobutyronitrile, stir evenly to obtain a mixed solution, and pour the mixed solution into constant pressure dropping funnel II; Step 2.3: Take a three-necked flask, fill it with nitrogen gas, and place constant-pressure dropping funnel I and constant-pressure dropping funnel II on opposite sides of the flask, setting the reaction temperature to 65-75°C. o C. Start stirring, then start adding liquid in constant pressure dropping funnel I and constant pressure dropping funnel II at the same dropping rate for 1-2 hours. After the addition is complete, continue stirring for 1-2 hours. When the viscosity reaches 5000-15000 cps, stop heating and add hydroquinone to terminate the reaction. Step 2.4: Add acrylic anhydride to the solution obtained in Step 2.3 and heat to 50-100°C. o C. React for 10-60 minutes. After the reaction is complete, add solvent to dilute and obtain the amphoteric resin.

4. The method for preparing amphoteric electrodeposition photoresist on a metal surface according to claim 1, characterized in that: In step 3, the electrophoretic paint is either acid-neutralized electrophoretic paint or alkali-neutralized electrophoretic paint.

5. The method for preparing amphoteric electrodeposition photoresist on a metal surface according to claim 4, characterized in that: In step 3, the preparation process of the acid-neutralized electrophoretic paint is as follows: Add the acidic substance to deionized water to obtain an acidic solution. Gradually add the acidic solution dropwise to the amphoteric resin. Stop adding the acidic solution when the pH reaches 4.5-6.

5. Continue to add deionized water to dilute the resin to a solid content of 0.1-20%. Then add a photoinitiator to obtain the acid-neutralized electrophoretic paint.

6. The method for preparing amphoteric electrodeposition photoresist on a metal surface according to claim 4, characterized in that: The preparation process of the alkali-neutralized electrophoretic paint is as follows: Add an alkaline substance to deionized water to obtain an alkaline solution; then gradually add the alkaline solution dropwise to the amphoteric resin. Stop adding the alkaline solution when the pH reaches 7.5-9.2, continue adding deionized water to dilute the resin to a solid content of 0.1-20%, and then add a photoinitiator to obtain the alkali-neutralized electrophoretic paint.

7. The method for preparing amphoteric electrodeposition photoresist on a metal surface according to claim 1, characterized in that: The specific process of step 4 is as follows: Electrophoretic paint is placed into an electrophoretic pool, two conductive substrates are inserted into both sides of the pool, and then a voltage of 20V-200V is applied for electrophoresis. The electrophoretic paint will deposit as a film on the conductive metal. Once the film thickness reaches 1µm-45µm, the power is turned off, and the electrophoretically deposited conductive substrate is placed in an oven at 45-150°C. o Baking at C for 1-2 hours yields a conductive substrate with photoresist deposited on it.

8. The method for preparing amphoteric electrodeposition photoresist on a metal surface according to claim 7, characterized in that: In step 4, the conductive metal is one of copper, nickel, aluminum, silver, gold, titanium, and palladium, and the substrate is polyimide, polyetherimide, glass fiber, polyethylene terephthalate, or blank.

9. A metal surface amphoteric electrodeposition photoresist, prepared by the preparation method of the metal surface amphoteric electrodeposition photoresist as described in any one of claims 1 to 8.

10. Application of amphoteric electrodeposition photoresist on metal surfaces in metal etching.

Images