A high-efficiency dewaxing cleaning solution for LED manufacturing process

Abstract

The application discloses a high-efficiency wax-removing cleaning solution for LED manufacturing process, which comprises the following components in the form of a total of 100% by mass: a pH regulator 0.1-5%, an organic alcohol ether solvent 70-90%, a rosin-based imidazoline sulfonate surfactant 0.1-5%, a wetting agent 0.1-1%, and deionized water 5-30%. The application aims to provide a LED wax-removing cleaning agent for cleaning the residual wax on the front surface of a chip and various contaminants on the back surface of the chip after waxing of an LED wafer. Compared with a traditional wax-removing solution, the application has the advantages of less volatile liquid, high cleaning life, high wax-removing cleanliness, protection of the chip electrode, reduction of the occurrence rate of glue gas pollution, and the ability to solve the common back-contamination problem in the industry, that is, the application has a strong cleaning and removing effect on organic contaminants such as residual polishing powder particles, latex fingerprints and various residual glue.

Description

Technical Field

[0001] This invention belongs to the field of LED manufacturing process, and particularly relates to a method for preparing a high-efficiency dewaxing cleaning solution. Background Technology

[0002] A light-emitting diode (LED) is a semiconductor device that converts electrical energy into visible light. It differs from the tungsten filament principle of incandescent lamps and the tri-color phosphor principle of energy-saving lamps. LEDs are made of group III-IV compound semiconductors (such as gallium arsenide (GaAs), gallium phosphide (GaP), and gallium arsenide phosphide (GaAsP)). When a forward voltage exceeding a certain value is applied, the diode emits light of a specific color; the exact color depends on the materials used in its manufacture.

[0003] The core of an LED is a chip composed of p-type and n-type semiconductors, with a transition layer between the two types of semiconductors called a pn junction. In the pn junction of certain semiconductor materials, when injected minority carriers recombine with majority carriers, they release excess energy in the form of light, thus directly converting electrical energy into light energy.

[0004] LEDs have advantages such as energy saving, high efficiency, durability, greenness, and environmental friendliness. After several years of rapid development, they have been applied in modern lighting, digital displays, and other fields. Moreover, the application of LEDs in various industries has promoted the manufacturing and use of semiconductor LEDs.

[0005] The LED industry is generally divided into three major stages according to the industrial chain: front-end (epitaxy growth), mid-end (chip manufacturing), and back-end (packaging process). Wax removal and cleaning of LED chips is a key post-processing step in the mid-end process of LED chip manufacturing. Its technical background stems from the need for temporary fixation in chip thinning and dicing processes, as well as the serious impact of residual wax layer on subsequent processes. At the same time, it continues to develop with the miniaturization of chips, the refinement of processes, and the upgrading of environmental protection requirements.

[0006] In the mid-stage manufacturing process of LED chips, the wafer thinning (backside grinding) and wafer dicing (cutting) stages rely on temporary bonding wax to stabilize and fix the wafer. During wafer thinning, the original wafer thickness is typically 500~700μm, and it needs to be thinned to 50~150μm to meet the heat dissipation and thickness requirements of subsequent dicing and packaging. The thinned wafer is extremely thin and fragile, so wax is used to bond the front side (functional side with electrodes and light-emitting structure) or back side of the wafer to a rigid carrier (alumina substrate) to provide mechanical support and prevent the wafer from warping or breaking during the grinding process.

[0007] Currently, commonly used temporary bonding waxes are high-molecular-weight organic waxes, mainly composed of rosin and long-chain fatty acids. If the wax layer and residues on the wafer are not completely removed after thinning and dicing, it will directly affect the yield and performance of all subsequent chip manufacturing processes, resulting in abnormalities such as electrode contact failure (Ni / Au, Ti / Al, etc.) caused by wax residue covering the metal electrodes on the chip surface, wire bonding failure, failure to meet brightness K-value test standards, and glue gas contamination.

[0008] Meanwhile, after the chip is thinned and polished, the back of the chip may still contain abrasive dirt from the polishing process, fingerprints from improper handling of latex gloves, and adhesive residue from labels. If the dirt on the back is not completely removed, it can easily lead to a decrease in dicing accuracy, an increase in chip chip breakage rate, cross-contamination of sorting equipment, and affect photoelectric performance, resulting in increased thermal resistance and decreased luminous efficiency.

[0009] Most commercially available temporary bonding wax cleaners can meet the requirements for removing residual wax from the front side of chips, but most of them have problems such as short cleaning life and weak cleaning power for dirt on the back side of chips. Patent CN114989903B mentions an LED solid wax cleaning composition using a water-based system. By compounding a rosin-based imidazoline nonionic surfactant, it can stably remove residual wax from the front side of chips. However, due to its water-based system, it mainly uses emulsification and dissolution. Under continuous heating cleaning operations, the solution evaporates rapidly (evaporation rate is approximately 5wt% / h), requiring constant replenishment of fresh solution, resulting in a short cleaning life. Furthermore, because the water-based system has a low proportion of organic solvents, it cannot effectively remove organic adhesive dirt from the back side. Additionally, the nonionic surfactant used has limited removal power for inorganic charged abrasive particles, leading to insufficient overall cleaning power for dirt on the back side of chips. Therefore, this invention is proposed. Summary of the Invention

[0010] This invention aims to provide a highly efficient wax removal and cleaning solution for LED manufacturing processes, used to clean residual wax on the front side and various contaminants on the back side of LED chips after wax removal. Compared with traditional wax removal solutions, this invention has the advantages of low evaporation, long cleaning life, high wax removal cleanliness, protection of chip electrodes, reduced glue gas contamination rate, and can solve common back contamination problems in the industry, namely, it also has a strong cleaning and removal effect on polishing powder particles, latex fingerprints, and various organic contaminants such as residual glue.

[0011] To achieve the above objectives, the present invention adopts the following technical solution: A high-efficiency dewaxing cleaning solution for LED manufacturing processes comprises the following components in a total mass percentage of 100%: pH adjuster 0.1-5%, organic alcohol ether solvent 70-90%, rosin-based imidazoline sulfonate surfactant 0.1-5%, wetting agent 0.1-1%, and deionized water 5-30%.

[0012] Furthermore, the structure of the rosin-based imidazoline sulfonate surfactant is as follows:

[0013] The preparation method of the rosin-based imidazoline sulfonate surfactant includes the following steps: 1) Synthesis of rosin-based imidazoline In a 500 mL straight four-necked flask equipped with a condenser, stirrer, and thermometer, 15.67 g of hydroxyethyl ethylenediamine, 17.5 g of rosin acid, and 0.9 g of phosphoric acid were added while nitrogen was introduced. The vacuum pump was turned on, and the residual vacuum pressure in the reaction system was adjusted to 20 kPa. The temperature was raised to 100 °C, and timing was started. The temperature was gradually increased to 170 °C over 3.5 h, and the mixture was aged for 2 h. Then, the temperature was raised to 220 °C to carry out the cyclization reaction until almost no water was distilled off. The residual vacuum pressure in the flask was adjusted to 0.25 kPa, and the excess hydroxyethyl ethylenediamine was distilled off to obtain approximately 25.54 g of rosinyl imidazoline.

[0014] 2) Synthesis of Rosin-based Imidazoline Sulfonate 115 g of deionized water, 17.5 g of ethanol, and 6 g of sodium hydroxide were added to the four-necked flask. The mixture was heated to 80 °C, and then 29.51 g of sodium 3-chloro-2-hydroxypropanesulfonate was added. After reacting for 6 hours, the chloride ion content no longer increased, and the conversion rate of rosinyl imidazoline was 91.9%. The reaction was then complete, yielding a transparent yellow viscous liquid. Ethanol was added, and after complete dissolution, the mixture was filtered. The filtrate was evaporated to dryness under negative pressure and recrystallized with acetone to obtain the rosinyl imidazoline sulfonate surfactant.

[0015]

[0016] Furthermore, the pH adjuster is one or more of isopropanolamine, triethanolamine, diethanolamine, N-butyldiethanolamine, 2-amino-2-methyl-1-propanol, N-ethylethanolamine, and monoethanolamine.

[0017] Furthermore, the organic alcohol ether solvent is one or more of ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and diethylene glycol methyl ether.

[0018] Furthermore, the wetting agent is one or more of the following: ammonium polycarboxylate, ethoxylated acetylacetonate, Tween 80, fatty alcohol ether carboxylate, and fatty amine polyoxyethylene ether.

[0019] Furthermore, the resistivity of the deionized water at 25°C is greater than 16 MΩ·cm.

[0020] Furthermore, the preparation method of the LED wax remover includes the following steps: 1) Mix deionized water and organic alcohol ether solvent and stir for 5-10 minutes; 2) Add rosin-based imidazoline sulfonate surfactant and wetting agent to the solution obtained in step (1), and stir for 10-30 min; 3) Add a pH adjuster to the solution obtained in step (2) and adjust the pH to 7-8; 4) Stop stirring and let stand at room temperature to obtain a transparent and clear homogeneous composition, which is the dewaxing cleaning solution.

[0021] The significant advantages of this invention are: This high-solvent system exhibits low evaporation of the cleaning solution. Its unique alcohol-ether structure provides excellent wax-dissolving properties, resulting in a long cleaning lifespan and effective removal of adhesive residues. The organic alcohol ether has a high boiling point (200-240℃), and even at high temperatures (70-90℃), the evaporation rate is low (approximately 0.15wt% / h). Its structure contains both ether bonds and hydroxyl groups. The ether bonds are highly hydrophobic at high temperatures, while the hydroxyl groups are hydrophilic. This unique amphiphilic structure allows it to act on both the non-polar and polar domains of rosin wax, giving the alcohol-ether solvent system excellent solubility and stability for waxes. Furthermore, the amphiphilic structure disrupts the molecular entanglement of adhesives, causing the dense adhesive film to gradually swell and soften, further breaking down the molecular aggregates of the adhesive into smaller molecule aggregates, thus achieving effective cleaning and removal.

[0022] The unique rosin-based imidazoline sulfonate surfactant enhances the emulsification and dissolution of rosin, providing excellent cleaning of abrasive particles and offering some protection to metal electrodes. Thanks to its head-group structure being identical to the rosin structure in wax, the principle of "like dissolves like" can be utilized to improve the emulsification and dissolution of rosin wax. Simultaneously, the sulfonic acid group in the structure is a strongly ionizing group, completely dissociating in water and adsorbing onto the particle surface to form a high-density negatively charged double layer. The strong electrostatic repulsion between similar particles effectively disperses particle agglomerates, efficiently removing residual grinding particles from the back of the wafer and synergistically dispersing wax particles to prevent re-adhesion. Furthermore, the lone pair electrons of the N atom in the imidazoline structure of this surfactant form coordinate bonds with the empty orbitals of metal atoms, allowing the imidazoline group to firmly adsorb onto the metal surface, forming a chemically adsorbed film that protects the chip electrodes from corrosive media and effectively reduces the incidence of adhesive gas contamination caused by die-attach adhesive adsorption during subsequent packaging processes. Attached Figure Description

[0023] Figure 1 This is a diagram of the LED chip electrodes after cleaning. Detailed Implementation

[0024] To make the above-mentioned features and advantages of the present invention more apparent and understandable, specific embodiments are described below in detail. Unless otherwise specified, the methods of the present invention are conventional methods in the art.

[0025] A high-efficiency dewaxing cleaning solution for LED manufacturing processes, comprising the following raw materials in 100% by mass percentage: pH adjuster 0.1-5%, organic alcohol ether solvent 70-90%, rosin-based imidazoline sulfonate surfactant 0.1-5%, wetting agent 0.1-1%, and deionized water 5-30%.

[0026] The pH adjuster is one or more of the following: isopropanolamine, diisopropylamine, diethylene glycolamine, triethanolamine, diethanolamine, N-butyldiethanolamine, ammonia, 2-amino-2-methyl-1-propanol, N-ethylethanolamine, monoethanolamine, tert-butylamine, and N-tert-butyldiethanolamine.

[0027] The organic alcohol ether solvent is one or more of ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol methyl ether, diethylene glycol butyl ether, dipropylene glycol butyl ether, tripropylene glycol butyl ether, and dipropylene glycol methyl ether.

[0028] The structural formula of the rosin-based imidazoline sulfonate surfactant is as follows: .

[0029] The preparation method of the rosin-based imidazoline sulfonate surfactant includes the following steps: 1) Synthesis of rosin-based imidazoline In a 500 mL straight four-necked flask equipped with a condenser, stirrer, and thermometer, 15.67 g of hydroxyethyl ethylenediamine, 17.5 g of rosin acid, and 0.9 g of phosphoric acid were added while nitrogen was introduced. The vacuum pump was turned on, and the residual vacuum pressure in the reaction system was adjusted to 20 kPa. The temperature was raised to 100 °C, and timing was started. The temperature was gradually increased to 170 °C over 3.5 h, and the mixture was aged for 2 h. The temperature was then raised to 220 °C to carry out the cyclization reaction until almost no water was distilled off. The residual vacuum pressure in the flask was adjusted to 0.25 kPa, and the excess hydroxyethyl ethylenediamine was distilled off to obtain approximately 25.54 g of rosinyl imidazoline.

[0030] 2) Synthesis of Rosin-based Imidazoline Sulfonate 115 g of deionized water, 17.5 g of ethanol, and 6 g of sodium hydroxide were added to the four-necked flask. The mixture was heated to 80 °C, and then 29.51 g of sodium 3-chloro-2-hydroxypropanesulfonate was added. After reacting for 6 hours, the chloride ion content no longer increased, and the conversion rate of rosin-based imidazoline was 91.9%. The reaction was then complete, yielding a transparent yellow viscous liquid. Ethanol was added, and after complete dissolution, the mixture was filtered. The filtrate was evaporated to dryness under negative pressure and recrystallized with acetone to obtain the rosin-based imidazoline sulfonate surfactant.

[0031]

[0032] Its structural characterization data are as follows: 1 H NMR (300Mhz, DMSO-d6), δ: 0.86 (m, 6H, CH3), 0.99 (t, 3H, CH3), 1.27 (s, 1H, CH), 1.30 (s, 2H, CH), 1 .44(m,2H,CH2),1.53(t,2H,CH2),1.62(s,2H,CH2),1.76(s,H,CH),1.92(m,2H,CH2),2.19(m,2H, CH2), 2.38 (s, 1H, CH), 2.42 (m, 2H, CH2), 3.30 (m, 4H, CH2), 3.43 (s, 2H, CH2), 3.50 (m, 2H, CH2), 3. 97 (m, 2H, CH2), 3.99 (m, 2H, CH2), 4.24 (m, 1H, OH), 4.77 (m, 1H, OH), 5.50 (s, 1H, H), 5.75 (s, 1H, H); 13 C NMR (125Mhz, DMSO-d6), δ: 14.1, 22.7, 31.9, 29.3, 29.6, 29.4, 22.6, 18.6, 26.5, 45.4, 45.7, 47.6, 56.3, 60.4, 125.7, 128.6, 129.0, 132.6, 159.1, 163.9, 194.7; HRMS calculated value C 26 H 42 N₂NaO₅S(M+H) + : 516.27, measured value: 517.48.

[0033] The wetting agent is one or more of the following: ammonium polycarboxylate, AEO-9, ethoxylated acetylacetonate, Tween 80, Span 20, fatty alcohol ether carboxylate, hyperbranched emulsifying and dispersing wetting agent, alkyl glycoside APG1214, and fatty amine polyoxyethylene ether.

[0034] The resistivity of the deionized water at 25°C is greater than 16 MΩ·cm.

[0035] The preparation method of the high-efficiency dewaxing cleaning solution includes the following steps: 1) Mix deionized water and organic alcohol ether solvent and stir for 5-10 minutes; 2) Add rosin-based imidazoline sulfonate surfactant and wetting agent to the solution obtained in step (1), and stir for 10-30 min; 3) Add a pH adjuster to the solution obtained in step (2) and adjust the pH to 7-8; 4) Stop stirring and let it stand until it reaches room temperature to obtain a transparent, clear and homogeneous composition.

[0036] To make the content of the present invention easier to understand, the technical solutions of the present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0037] Table 1 Components and their contents in different dewaxing cleaning solutions

[0038]

[0039] Comprehensive performance tests were carried out on Examples 1-5 and Comparative Examples 1-4: (1) Performance 1: Test of the carbon content on the front side of the chip after dewaxing cleaning Take a 4-inch wafer with evenly wax-coated front side (about 0.12 g) for cleaning test. The cleaning process is as follows: ultrasonic cleaning in liquid medicine tank 1 at 85 °C for 10 min → ultrasonic cleaning in liquid medicine tank 2 at 85 °C for 10 min → pure water spray at room temperature for 5 min → drying at 90 °C / 15 min. (The ultrasonic conditions are all 1 A current / 40 kHz). After continuously cleaning 1500 pieces in a 25 L liquid medicine tank, take the 1500th cleaned chip and perform EDS detection on the surface carbon element content at the electrode (as Figure 1 shown). The lower the carbon content, the higher the front side dewaxing cleanliness. If the carbon content is higher than 5%, it is determined that the dewaxing is not clean.

[0040] (2) Performance 2: Test of the number of particles on the back side of the chip after dewaxing cleaning The cleaning parameters are the same as those in Performance 1 test. Place the cleaned wafer with the back side facing up on the vacuum adsorption stage of the AOI machine (automatic optical inspection equipment), and ensure full coverage of the detection area through flat edge positioning. Select the dark field mode, set the particle size threshold ≥ 1 μm, and perform a full-chip scan. If the number of detected particles < 500, it is qualified.

[0041] (3) Performance 3: Test of the chip electrode protection effect (adhesive gas pollution) Use Feedpool EP-3600-A8-1 die bonding glue to conduct a simulation experiment of deteriorating adhesive gas pollution. The better the electrode protection effect, the lower the surface adhesive gas pollution ratio. Take 8 groups of chips of different batches (all gold electrodes). Fix the 8 groups of chips on the substrate, place the substrate flat in a petri dish, and at the same time evenly apply about 0.1 g of die bonding glue under the substrate. Seal the petri dish with high-temperature resistant glue and place it in an oven for baking at 300 °C for 3 hours to simulate the pollution experiment of the volatile substances of the die bonding glue on the chip in the baking environment. Then use an electron microscope to observe and calculate the proportion of the chip groups affected by adhesive gas pollution. If the adhesive gas pollution ratio is greater than 50%, it is unqualified.

[0042] Table 2 Performance test results of different wax removers

[0043] As can be seen from Tables 1 and 2, all performance tests of Examples 1, 2, 3, 4, and 5 were OK after dewaxing.

[0044] Compared with Example 3, Comparative Example 1 did not add a pH adjuster, and the overall solution was acidic. The rosin acid component existed in molecular form. However, in Example 3, the solution was neutral, and the rosin acid ionized into rosin salt. At this time, the ionization state, adsorption capacity, and structural matching degree of the rosin imidazoline sulfonate surfactant were all optimal, which could form an O / W type rosin emulsion with uniform particle size and high stability. This helped to emulsify and dissolve rosin wax, and the adsorption effect of the surfactant on the particles was optimal. Therefore, without a pH adjuster, the dewaxing and particle cleaning effect of Comparative Example 1 decreased under acidic conditions.

[0045] Compared with Example 3, Comparative Example 2 did not add alcohol ether solvent, which resulted in the overall system lacking the wax-dissolving effect of similar dissolving substances. The wax-dissolving limit was greatly reduced, and the emulsifying and dissolving effect of rosin-based imidazoline sulfonate alone could not achieve the cleaning of a large amount of wax scale. At the end of the cleaning process, the residual wax on the surface increased, which led to a significant increase in the carbon content on the front side.

[0046] Compared with Example 3, Comparative Example 3 did not add rosin-based imidazoline sulfonate, resulting in a lack of emulsification and dissolution effect on rosin wax, failure of charged adsorption effect on particles, and failure of electrode protection effect. Therefore, its performance was NG.

[0047] Compared with Example 3, Comparative Example 4 did not add a wetting agent, which led to a decrease in interfacial tension and a certain degree of impact on the ability of the drug solution to penetrate and spread. This made it easier for wax to be deposited again, resulting in an increase in surface carbon content.

[0048] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A high-efficiency dewaxing and cleaning solution for LED manufacturing processes, characterized in that, The product is composed of the following raw materials in the following mass percentages, totaling 100%: pH adjuster 0.1-5%, organic alcohol ether solvent 70-90%, rosin-based imidazoline sulfonate surfactant 0.1-5%, wetting agent 0.1-1%, and deionized water 5-30%.

2. The dewaxing cleaning solution according to claim 1, characterized in that, The pH adjuster is one or more of the following: isopropanolamine, diisopropylamine, diethylene glycolamine, triethanolamine, diethanolamine, N-butyldiethanolamine, ammonia, 2-amino-2-methyl-1-propanol, N-ethylethanolamine, monoethanolamine, tert-butylamine, and N-tert-butyldiethanolamine.

3. The dewaxing cleaning solution according to claim 1, characterized in that, The organic alcohol ether solvent is one or more of ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol methyl ether, diethylene glycol butyl ether, dipropylene glycol butyl ether, tripropylene glycol butyl ether, and dipropylene glycol methyl ether.

4. The dewaxing cleaning solution according to claim 1, characterized in that, The structural formula of the rosin-based imidazoline sulfonate surfactant is as follows: 。 5. The dewaxing cleaning solution according to claim 1, characterized in that, The wetting agent is one or more of the following: ammonium polycarboxylate, AEO-9, ethoxylated acetylacetonate, Tween 80, Span 20, fatty alcohol ether carboxylate, hyperbranched emulsifying and dispersing wetting agent, alkyl glycoside APG1214, and fatty amine polyoxyethylene ether.

6. The dewaxing cleaning solution according to claim 1, characterized in that, The resistivity of the deionized water at 25°C is greater than 16 MΩ·cm.

7. The dewaxing cleaning solution according to claim 1, characterized in that, The preparation method of the dewaxing cleaning solution includes the following steps: 1) Mix deionized water and organic alcohol ether solvent and stir for 5-10 minutes; 2) Add rosin-based imidazoline sulfonate surfactant and wetting agent to the solution obtained in step (1), and stir for 10-30 min; 3) Add a pH adjuster to the solution obtained in step (2) and adjust the pH to 7-8; 4) Stop stirring and let stand at room temperature to obtain a clear and homogeneous composition.

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