Silver etching solution and preparation method and application thereof
By adding main etching agents such as phosphoric acid, nitric acid, acetic acid and polyethylene glycol-functionalized lipoic acid polymers to the silver etching solution, a nano-corrosion layer is formed and viscosity is reduced, and silver residue and aluminum damage problems are solved, and an efficient etching and long-life etching solution is used in OLED.
Patent Information
- Application Number
- CN202510990273.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-18
- Publication Date
- 2025-08-15
AI Technical Summary
The existing silver etching liquid has silver residue and aluminum damage problems during the etching process, and its service life is short, which cannot meet the needs of high-precision flat panel display OLEDs.
Using phosphoric acid, nitric acid and acetic acid as the main etchant, carboxylic acid, inorganic salt and polyethylene glycol functionalized lipoic acid polymers are added to form a nano-corrosion layer through disulfide bonds, reducing viscosity and suppressing fluctuations in silver ion concentration, and combining a viscosity-reducing agent to reduce silver residue and aluminum damage.
Effectively reduce silver residue and aluminum damage, improve etching quality and efficiency, ensure pattern edge clarity, extend the service life of the etching liquid, and is suitable for high-precision flat panel display OLED process.
Smart Images
Figure CN120485781A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of etching, and in particular relates to a silver etching solution and a preparation method and application thereof. Background Art
[0002] With the development of the information age, display technology has advanced rapidly, with semiconductor displays, in particular, attracting considerable attention. Current mainstream flat panel display technologies include liquid crystal displays (LCDs), plasma displays (PDPs), electroluminescent displays (ELDs), and organic light-emitting diodes (OLEDs). OLEDs, due to their self-luminous properties and low-voltage drive, are widely used in small displays for portable devices.
[0003] In OLED manufacturing, silver is often used as a thin film material for cathodes and anodes due to its excellent conductivity and ductility. However, wet etching processes often use acidic etchants such as phosphoric acid, nitric acid, and acetic acid to etch silver-containing films. This can corrode the aluminum layer in the signal transmission lines (Ti-Al-Ti), causing the aluminum line width to narrow, thereby affecting the transmission performance of the optoelectronic signal.
[0004] Currently, CN116200749A provides an etching solution for a multilayer film containing indium oxide or its alloy / silver or its alloy, the etching solution comprising the following components: nitric acid, phosphoric acid, acetic acid, a corrosion inhibitor, and water; the corrosion inhibitor is selected from at least one of an organic acid or its salt, an azole, or its derivatives; the etching solution can effectively balance the relationship between the etching rate and the degree of corrosion in a short-term process, so that the etching solution has the advantages of low side etching, low Al corrosion, good etching effect, and no residue. However, it cannot completely solve the problems of silver residue, long-term aluminum damage, and short etching solution life.
[0005] Based on the above situation, it is necessary to propose a silver etching solution and its preparation method and application to improve the problems of silver residue, aluminum damage and service life performance. Summary of the Invention
[0006] Based on this, the object of the present invention is to provide a silver etching solution and a preparation method and application thereof, which are helpful to improve the problems of silver residue, aluminum damage and service life performance.
[0007] In a first aspect, the present invention provides a silver etching solution comprising the following components in percentage by mass: 55-60% phosphoric acid, 5-10% nitric acid, 10-15% acetic acid, 5-8% hydroxyl-containing carboxylic acid, 0.5-1% inorganic salt, 0.1-0.3% polyethylene glycol-functionalized lipoic acid polymer, 1-3% viscosity reducer, and the balance being water.
[0008] Preferably, the silver etching solution comprises the following components in mass percentage: 57-59% phosphoric acid, 7-9% nitric acid, 12-14% acetic acid, 6-7% hydroxyl-containing carboxylic acid, 0.8-0.9% inorganic salt, 0.15-0.25% polyethylene glycol functionalized lipoic acid polymer, 1.5-2.5% viscosity reducer, and the balance is water.
[0009] Preferably, the silver etching solution comprises the following components in mass percentage: 58.5% phosphoric acid, 8% nitric acid, 13% acetic acid, 6.5% hydroxyl-containing carboxylic acid, 0.85% inorganic salt, 0.2% polyethylene glycol-functionalized lipoic acid polymer, 2% viscosity reducer, and the balance is water.
[0010] Preferably, the polyethylene glycol functionalized lipoic acid polymer comprises at least one of double-ended lipoic acid polyethylene glycol, lipoic acid-polyethylene glycol-carboxyl, lipoic acid-polyethylene glycol-thiol, and lipoic acid-polyethylene glycol-maleimide.
[0011] Preferably, the viscosity reducing agent includes at least one of sodium carboxymethyl cellulose, hydroxyethyl cellulose, sodium lignin sulfonate, sodium hexametaphosphate, sodium tripolyphosphate, sodium alginate, and xanthan gum.
[0012] Preferably, the carboxylic acid containing a hydroxyl group includes at least one of citric acid, malic acid, 3-hydroxypropionic acid, β-hydroxybutyric acid, salicylic acid, p-hydroxybenzoic acid, and tartaric acid.
[0013] Preferably, the inorganic salt includes at least one of potassium nitrate, sodium nitrate, ammonium nitrate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, ammonium dihydrogen phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, and diammonium phosphate.
[0014] In a second aspect, the present invention provides a method for preparing a silver etching solution, comprising the following steps: Phosphoric acid, nitric acid and acetic acid are mixed to obtain a mixed acid; carboxylic acid containing hydroxyl groups and inorganic salts are dissolved in water, and polyethylene glycol functionalized lipoic acid polymer, viscosity reducer and mixed acid are added, stirred and filtered to obtain a silver etching solution.
[0015] In a third aspect, the present invention provides a silver etching solution for use in flat panel displays (OLEDs).
[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The silver etching solution of the present invention contains a polyethylene glycol-functionalized lipoic acid polymer, and its lipoic acid (LA) contains a disulfide bond, which can form a monomolecular self-assembled film on the surface of aluminum through the disulfide bond action, forming a dense nano-corrosion barrier layer, effectively isolating the silver etching solution and preventing aluminum from being damaged; and the disulfide bond in the polyethylene glycol-functionalized lipoic acid polymer can coordinate with silver ions, which can suppress the fluctuation of etching characteristics caused by the increase of silver ion concentration, stabilize the etching effect, and maintain the characteristics of the new solution even after the number of processed sheets is superimposed, so that it can be used repeatedly for a long time.
[0017] (2) Since the etching solution system contains a large amount of phosphoric acid, the viscosity of the etching solution is relatively high, the corrosion rate of the signal transmission line (Ti-Al-Ti) is accelerated, and a large amount of silver residue is caused around the transmission line. The addition of a viscosity reducer to the silver etching solution of the present invention can reduce the viscosity of the etching system without affecting the etching effect, reduce the corrosion of the signal transmission line, and facilitate the diffusion of silver ions without causing silver residue.
[0018] (3) The silver etching solution of the present invention uses phosphoric acid, nitric acid and acetic acid as main etching agents, carboxylic acids containing hydroxyl groups and inorganic salts as auxiliary etching agents, and polyethylene glycol-functionalized lipoic acid polymers and viscosity reducers to improve the quality and efficiency of etching, reduce silver residue and aluminum damage, ensure clear pattern edges and smooth surface, and have a long service life. It is suitable for flat panel display OLED processes with high precision requirements. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 (a) is a SEM image after etching with the silver etching solution (new solution) of Example 1; (b) is a FIB image after etching with the silver etching solution (new solution) of Example 1.
[0020] Figure 2 (a) is the SEM image after etching with the silver etching solution (old solution) of Example 1; (b) is the FIB image after etching with the silver etching solution (old solution) of Example 1.
[0021] Figure 3 (a) is the SEM image after etching with the silver etching solution (new solution) of Comparative Example 3; (b) is the FIB image after etching with the silver etching solution (new solution) of Comparative Example 3.
[0022] Figure 4 (a) is the SEM image after etching with the silver etching solution (old solution) of Comparative Example 3; (b) is the FIB image after etching with the silver etching solution (old solution) of Comparative Example 3. DETAILED DESCRIPTION
[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.
[0024] Example 1 A silver etching solution comprises the following components in percentage by weight: 55% phosphoric acid, 5% nitric acid, 10% acetic acid, 5% citric acid, 0.5% potassium nitrate, 0.1% double-ended lipoic acid polyethylene glycol, 1% sodium hexametaphosphate, and the balance being water; A method for preparing a silver etching solution comprises the following steps: Phosphoric acid, nitric acid and acetic acid are mixed to obtain a mixed acid; citric acid and potassium nitrate are dissolved in water, and double-terminated lipoic acid polyethylene glycol, sodium hexametaphosphate and the mixed acid are added, stirred, and filtered to obtain a silver etching solution.
[0025] Example 2 A silver etching solution comprises the following components in percentage by weight: 57% phosphoric acid, 7% nitric acid, 12% acetic acid, 6% malic acid, 0.8% sodium nitrate, 0.15% lipoic acid-polyethylene glycol-carboxyl, 1.5% sodium carboxymethyl cellulose, and the balance is water; A method for preparing a silver etching solution comprises the following steps: Phosphoric acid, nitric acid and acetic acid are mixed to obtain a mixed acid; malic acid and sodium nitrate are dissolved in water, and lipoic acid-polyethylene glycol-carboxyl, sodium carboxymethyl cellulose and the mixed acid are added, stirred, and filtered to obtain a silver etching solution.
[0026] Example 3 A silver etching solution comprises the following components in percentage by weight: 58.5% phosphoric acid, 8% nitric acid, 13% acetic acid, 6.5% salicylic acid, 0.85% sodium dihydrogen phosphate, 0.2% thioctic acid-polyethylene glycol-mercapto group, 2% sodium lignin sulfonate, and the balance being water; A method for preparing a silver etching solution comprises the following steps: Phosphoric acid, nitric acid and acetic acid are mixed to obtain a mixed acid; salicylic acid and sodium dihydrogen phosphate are dissolved in water, and lipoic acid-polyethylene glycol-mercapto group, sodium lignin sulfonate and the mixed acid are added, stirred, and filtered to obtain a silver etching solution.
[0027] Example 4 A silver etching solution comprises the following components in percentage by weight: 59% phosphoric acid, 9% nitric acid, 14% acetic acid, 7% 3-hydroxypropionic acid, 0.9% ammonium nitrate, 0.25% lipoic acid-polyethylene glycol-maleimide, 2.5% sodium tripolyphosphate, and the balance being water; A method for preparing a silver etching solution comprises the following steps: Phosphoric acid, nitric acid and acetic acid are mixed to obtain a mixed acid; 3-hydroxypropionic acid and ammonium nitrate are dissolved in water, and lipoic acid-polyethylene glycol-maleimide, sodium tripolyphosphate and the mixed acid are added, stirred, and filtered to obtain a silver etching solution.
[0028] Example 5 A silver etching solution comprises the following components in percentage by weight: 60% phosphoric acid, 10% nitric acid, 15% acetic acid, 8% tartaric acid, 1% potassium dihydrogen phosphate, 0.3% double-ended lipoic acid polyethylene glycol, 3% sodium alginate, and the balance being water; A method for preparing a silver etching solution comprises the following steps: Phosphoric acid, nitric acid and acetic acid are mixed to obtain a mixed acid; tartaric acid and potassium dihydrogen phosphate are dissolved in water, and double-terminated lipoic acid polyethylene glycol, sodium alginate and the mixed acid are added, stirred, and filtered to obtain a silver etching solution.
[0029] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that double-capped lipoic acid polyethylene glycol (double-capped lipoic acid polyethylene glycol) is not added, specifically as follows: A silver etching solution comprising the following components in percentage by weight: 55% phosphoric acid, 5% nitric acid, 10% acetic acid, 5% citric acid, 0.5% potassium nitrate, 1% sodium hexametaphosphate, and the balance being water; A method for preparing a silver etching solution comprises the following steps: Phosphoric acid, nitric acid and acetic acid are mixed to obtain a mixed acid; citric acid and potassium nitrate are dissolved in water, and sodium hexametaphosphate and the mixed acid are added, stirred, and filtered to obtain a silver etching solution.
[0030] Comparative Example 2 The only difference between Comparative Example 2 and Example 1 is that no viscosity reducer (sodium hexametaphosphate) is added, and the details are as follows: A silver etching solution comprises the following components in percentage by weight: 55% phosphoric acid, 5% nitric acid, 10% acetic acid, 5% citric acid, 0.5% potassium nitrate, 0.1% double-ended lipoic acid polyethylene glycol, and the balance being water; A method for preparing a silver etching solution comprises the following steps: Phosphoric acid, nitric acid and acetic acid are mixed to obtain a mixed acid; citric acid and potassium nitrate are dissolved in water, and double-terminated lipoic acid polyethylene glycol and the mixed acid are added, stirred, and filtered to obtain a silver etching solution.
[0031] Comparative Example 3 A silver etching solution comprising the following components in percentage by weight: 41% phosphoric acid, 1% nitric acid, 14% acetic acid, 0.25% aminotri(methylenephosphonic) acid, and the balance being water; A method for preparing a silver etching solution comprises the following steps: Phosphoric acid, nitric acid and acetic acid are mixed, added into water, and aminotrimethylenephosphonic acid is added, stirred and filtered to obtain a silver etching solution.
[0032] Performance Testing OLED display panels are divided into a packaging module and a pixel region. The packaging module contains Al process circuitry, primarily providing internal and external circuit connections. The pixel region, the core display area, is primarily responsible for light emission and modulation and is composed of ITO / Ag / ITO. OLED samples requiring etching were immersed in the silver etching solution obtained in Examples 1-5 and Comparative Examples 1-3 of the present invention at 40°C for 60 seconds, followed by a 1-minute rinse with ultrapure water and finally dried with high-purity nitrogen.
[0033] 1. Evaluation of the number of sheets processed: The silver etching solutions prepared in Examples 1-5 and Comparative Examples 1-3 are referred to as new solutions. Silver etching solutions prepared after a long etching process, where 1000 ppm of silver powder was artificially dissolved (evaluated by the number of sheets processed), are referred to as old solutions.
[0034] Silver residue and aluminum damage were evaluated using each of the new and old solutions according to the following methods.
[0035] 2. Evaluation of Silver Residue: To evaluate the degree of silver residue after etching in the silver etching solutions prepared in Examples 1-5 and Comparative Examples 1-3, a scanning electron microscope (SEM) was used to determine whether silver residue was formed by measuring the area of the residual metal film in the region between the ITO / Ag / ITO wiring. Silver residue evaluation criteria: ●: no silver residue; ▲: small amount of silver residue; ■: large amount of silver residue.
[0036] 3. Aluminum Damage Evaluation: To evaluate the extent of aluminum damage in the Ti-Al-Ti alloy during the silver etching process of Examples 1-5 and Comparative Examples 1-3, a focused ion beam (FIB) microscope was used to evaluate the aluminum damage. Aluminum Damage Evaluation: Top is the horizontal distance between the upper Ti layer and the extended length of the intermediate Al metal; bottom is the horizontal distance between the lower Ti layer and the extended length of the intermediate Al metal: A: Top value less than 300nm, and Bottom value less than 350nm; B: Top value between 300nm and 350nm, or Bottom value between 350nm and 400nm; C: Top value greater than 350nm, and Bottom value greater than 400nm.
[0037] in, Figure 1 (a) is a SEM image after etching with the silver etching solution (new solution) of Example 1; (b) is a FIB image after etching with the silver etching solution (new solution) of Example 1.
[0038] Figure 2 (a) is the SEM image after etching with the silver etching solution (old solution) of Example 1; (b) is the FIB image after etching with the silver etching solution (old solution) of Example 1.
[0039] Figure 3 (a) is the SEM image after etching with the silver etching solution (new solution) of Comparative Example 3; (b) is the FIB image after etching with the silver etching solution (new solution) of Comparative Example 3.
[0040] Figure 4 (a) is the SEM image after etching with the silver etching solution (old solution) of Comparative Example 3; (b) is the FIB image after etching with the silver etching solution (old solution) of Comparative Example 3.
[0041] The specific test results are shown in Table 1: Table 1
[0042] Combine Figure 1-4 As shown in Table 1, the etching effects of the silver etching solutions obtained in Examples 1-5 of the present invention are significantly better than those in Comparative Examples 1-3.
[0043] Comparing Example 1 with Comparative Example 1, it can be seen that the addition of double-ended lipoic acid polyethylene glycol to the silver etching solution of the present invention greatly reduces the damage of the silver etching solution to the metal aluminum layer in Ti-Al-Ti, and also helps to extend the service life of the silver etching solution; comparing Example 1 with Comparative Example 2, it can be seen that the addition of a viscosity reducer to the silver etching solution of the present invention is beneficial to improving the undesirable phenomenon of silver residue; from Example 1 to Comparative Example 3, it can be seen that compared with the existing silver etching solution (phosphoric acid, nitric acid, acetic acid, aminotri(methylenephosphonic acid), the components in the silver etching solution formula of the present invention interact with each other, improve the problems of silver residue and aluminum damage, and extend the service life of the etching solution.
[0044] It should be noted that the above disclosed embodiments only reflect the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, anyone familiar with the technical field should understand that modifications or various changes, equivalent substitutions, without departing from the scope of the technical solution of the present invention, should all fall within the scope of protection of the present invention.
Claims
1. A silver etching solution, characterized in that The invention comprises the following components in percentage by mass: 55-60% phosphoric acid, 5-10% nitric acid, 10-15% acetic acid, 5-8% carboxylic acid containing hydroxyl group, 0.5-1% inorganic salt, 0.1-0.3% polyethylene glycol functionalized lipoic acid polymer, 1-3% viscosity reducer, and the balance is water.
2. The silver etching solution according to claim 1, wherein The invention comprises the following components in percentage by mass: 57-59% phosphoric acid, 7-9% nitric acid, 12-14% acetic acid, 6-7% carboxylic acid containing hydroxyl group, 0.8-0.9% inorganic salt, 0.15-0.25% polyethylene glycol functionalized lipoic acid polymer, 1.5-2.5% viscosity reducer, and the balance is water.
3. The silver etching solution according to claim 2, wherein The invention comprises the following components in percentage by weight: 58.5% phosphoric acid, 8% nitric acid, 13% acetic acid, 6.5% carboxylic acid containing hydroxyl group, 0.85% inorganic salt, 0.2% polyethylene glycol functionalized lipoic acid polymer, 2% viscosity reducer, and the balance is water.
4. The silver etching solution according to claim 1, wherein The polyethylene glycol functionalized lipoic acid polymer comprises at least one of double-ended lipoic acid polyethylene glycol, lipoic acid-polyethylene glycol-carboxyl, lipoic acid-polyethylene glycol-sulfhydryl, and lipoic acid-polyethylene glycol-maleimide.
5. The silver etching solution according to claim 1, wherein The viscosity reducing agent includes at least one of sodium carboxymethyl cellulose, hydroxyethyl cellulose, sodium lignin sulfonate, sodium hexametaphosphate, sodium tripolyphosphate, sodium alginate, and xanthan gum.
6. The silver etching solution according to claim 1, wherein The carboxylic acid containing a hydroxyl group includes at least one of citric acid, malic acid, 3-hydroxypropionic acid, β-hydroxybutyric acid, salicylic acid, p-hydroxybenzoic acid, and tartaric acid.
7. The silver etching solution according to claim 1, wherein The inorganic salt includes at least one of potassium nitrate, sodium nitrate, ammonium nitrate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, ammonium dihydrogen phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, and diammonium phosphate.
8. A method for preparing the silver etching solution according to any one of claims 1 to 7, characterized in that: The following steps are involved: Phosphoric acid, nitric acid and acetic acid are mixed to obtain a mixed acid; carboxylic acid containing hydroxyl groups and inorganic salts are dissolved in water, and polyethylene glycol functionalized lipoic acid polymer, viscosity reducer and mixed acid are added, stirred and filtered to obtain a silver etching solution.
9. A silver etching solution according to any one of claims 1 to 7 or a silver etching solution prepared by the preparation method according to claim 8, applied to a flat panel display (OLED).