Glass selective environment-friendly etching solution and special equipment thereof

Abstract

The invention discloses a glass selective environment-friendly etching solution and special equipment thereof, and belongs to the technical field of microelectronic manufacturing and advanced packaging. The etching liquid comprises potassium hydroxide, potassium carbonate, a composite wetting penetrant and a multi-mechanism scale inhibition dispersant, can realize high-efficiency and high-selectivity etching of a laser modified area of glass at a room temperature of about 20 DEG C, and effectively inhibits deposition of by-products. The special equipment is of a double-sided alternate wave scouring type structure, and through alternate reciprocating motion of symmetrically-arranged push plates, liquid flows which are strongly oriented and periodically reversed are generated on the two sides of a glass plate array, and efficient scouring and mass transfer updating of the double faces of the glass plates and the interiors of through holes are achieved. According to the invention, the environment-friendly etching liquid is combined with special physical washing equipment, so that efficient coordination of chemical dispersion and physical washing is formed, the problems of high temperature, high toxicity, easiness in blockage of deep holes and poor uniformity of the traditional process are solved, and a complete solution is provided for green, low-cost and large-scale production of a glass through hole technology.

Description

Technical Field

[0001] This invention belongs to the field of microelectronics manufacturing and advanced packaging technology, specifically relating to a laser-induced wet etching technology for manufacturing through-glass vias (TGV). More specifically, this invention relates to an environmentally friendly alkaline etching solution formulation that is completely free of hydrofluoric acid and its derivative fluorides, can operate efficiently at room temperature, and a dedicated double-sided alternating wave-washing auxiliary device that works in conjunction with this formulation. Background Technology

[0002] As electronic devices develop towards miniaturization, high performance, and three-dimensional integration, glass through-hole technology has become a key technology in fields such as 2.5D / 3D advanced packaging, radio frequency devices, microelectromechanical systems, and optoelectronic integration due to its excellent high-frequency performance, thermal stability, and cost advantages.

[0003] Among the various TGV manufacturing processes, laser-induced etching (LAI) technology has attracted considerable attention due to its ability to process high-precision, high aspect ratio, and complex three-dimensional structures. This technology typically involves two steps: first, a laser is used to scan and modify specific areas within the glass, disrupting its stable silicon-oxygen network structure; then, a chemical etching solution is used to selectively and anisotropically dissolve the modified areas, thereby forming vias, cavities, or channels. Compared to traditional direct laser ablation, LAI produces almost no heat-affected zone and yields microstructures with smoother hole walls and more controllable shapes.

[0004] However, the large-scale application of this technology faces severe etching process bottlenecks. Currently, mainstream etching solution systems heavily rely on hydrofluoric acid or its salts. Although hydrofluoric acid has a fast etching rate, its high toxicity, strong volatility, and extreme hazards to equipment and human health (such as the risk of irreversible tissue damage and organ failure) result in extremely high production safety costs. Furthermore, hydrofluoric acid etching is inherently isotropic, with limited selectivity between modified and unmodified regions, easily leading to lateral drilling, affecting the precision control of via morphology, and its wastewater treatment is difficult, posing significant environmental risks.

[0005] To mitigate the risks associated with hydrofluoric acid, the industry has explored fluoride-containing salts (such as ammonium fluoride and potassium fluoride) and strongly alkaline etching solutions. While fluoride-containing salts improve operational safety to some extent, they still rely on the corrosive effects of fluoride ions, failing to completely solve the environmental problems associated with fluoride-containing wastewater. Furthermore, they often exhibit insufficient stability and narrow process windows in large-scale applications. Alkaline etching solutions, represented by potassium hydroxide, demonstrate good chemoselectivity for laser-modified glass, but their industrialization faces two major challenges: First, to achieve acceptable etching rates and prevent the rapid deposition of byproducts (such as silica gel), traditional alkaline etching must be performed at high temperatures (typically >70°C). This not only consumes a lot of energy but also leads to the volatilization of etching solution components, concentration instability, and potential glass breakage due to thermal stress. Second, when etching high aspect ratio deep holes, the silicates generated in the reaction and the metal ions dissolved from the glass or equipment (such as Ca2+) pose significant risks. 2+ Al 3+ The resulting precipitates easily deposit and adhere firmly within the pores, severely clogging the channels. Conventional ultrasonic or mechanical stirring suffers from drawbacks when processing densely packed glass plate arrays in large-scale production, including rapid energy decay, uneven mass transfer, and a tendency to cause overall liquid temperature rise, failing to effectively solve the cleaning challenges inside deep pores. Recent advancements have addressed similar mass transfer and cleaning issues, such as nitrogen bubbling technology. This technology generates uniform and controllable bubbles to improve the transport efficiency of chemical solutions within microstructures, effectively preventing secondary deposition of byproducts. This indirectly confirms the importance of active fluid disturbance for wet etching processes of high aspect ratio structures. However, bubbling technology easily forms stable bubbles in liquid environments containing surfactants, clogging pore-like structures and hindering effective etching. Simultaneously, traditional wet etching technology is also driven by environmental requirements, constantly pushing for technological innovation, such as using environmentally friendly reagents and reducing harmful gases generated during processing.

[0006] Therefore, developing an etching solution that can perform patterned etching with high selectivity at room temperature, is environmentally friendly, has a high etching rate, and can effectively suppress and remove by-product deposition in deep holes through a synergistic chemical and physical mechanism is crucial for promoting the green, low-cost, and large-scale application of laser-induced etching technology. Summary of the Invention

[0007] To address the environmental hazards of hydrofluoric acid etching solutions and the high temperature and low efficiency of alkaline etching processes in existing technologies, this invention aims to provide an environmentally friendly glass etching solution formulation. This formulation not only avoids the use of hydrofluoric acid but also enables highly efficient selective etching of glass at near room temperature, reliably removing silica or gel deposits within glass pores. Simultaneously, a mechanical wave-generating device is provided to overcome the shortcomings of traditional stirring, ultrasonication, and bubbling methods in processing glass arrays, such as uneven mass transfer, uncontrolled temperature rise, and foam generation. This device achieves efficient renewal and double-sided scouring of the etching solution within narrow gaps and deep pores of the glass, significantly improving etching efficiency and precision through synergistic effects with the etching solution.

[0008] To achieve the above objectives, the present invention provides the following mutually synergistic technical solutions: In a first aspect, the present invention provides a glass selective environmentally friendly etching solution, which is a water-based alkaline solution containing the following components per liter of solution: a) Main etchant: 3.0–4.0 mol / L potassium hydroxide; b) pH buffer and stabilizer: 0.2–0.5 mol / L potassium carbonate; c) A composite wetting and penetration system comprising: 0.1% to 0.2% by volume of a nonionic surfactant and 1% to 3% by volume of a short-chain alcohol; d) A multi-mechanism scale inhibition and dispersion system, comprising: 5–15 mmol / L of metal ion chelating agent and 0.02–0.05 mol / L of ammonia.

[0009] Preferably, the nonionic surfactant is APG-0810 or Tween-20.

[0010] Preferably, the short-chain alcohol is ethanol or glycerol.

[0011] Preferably, the metal ion chelating agent is disodium ethylenediaminetetraacetate or sodium citrate.

[0012] Preferably, the multi-mechanism scale inhibitor and dispersion system further comprises 100-300 ppm of a polymeric dispersant, wherein the polymeric dispersant is polyepoxysuccinic acid or low molecular weight polyacrylic acid.

[0013] Secondly, the present invention provides a special device for alternating wave washing of both sides of a glass plate, used in conjunction with the above-mentioned etching solution, comprising: Tank 1 is used to hold the etching solution; The trough cover 4 covers the trough body 1 and has a straight groove in the center with hollow sections at both ends. A substrate fixing array is disposed in the groove 1 for vertically clamping multiple glass substrates arranged in parallel. A bidirectional wave generator is used to drive two push plates 3, which are symmetrically arranged on both sides of the substrate fixing array, to perform alternating reciprocating linear motion, so as to generate periodically changing directional liquid flow in the etching solution to scour both sides of the glass substrate.

[0014] Preferably, the bidirectional wave generator includes a drive motor 9, an intermittent gear 10 driven by the drive motor 9, and a unicircular ring 6 with two parallel rack segments on its inner side; the intermittent gear 10 alternately meshes with the two parallel rack segments in one rotation cycle, converting the continuous rotational motion of the motor into the reciprocating linear motion of the unicircular ring 6; the unicircular ring 6 is connected to two push plates 3 through a sliding plate 5 to drive the synchronous reciprocating motion of the push plates 3.

[0015] Preferably, the sliding plate 5 is embedded in the straight groove of the groove cover 4 and can slide along the straight groove. The push plate 3 is connected to the sliding plate 5 through the hollow sections at both ends of the straight groove. The sliding plate 5 closes the hollow sections at both ends of the straight groove to prevent liquid from splashing out.

[0016] Preferably, the device also includes a slot cover lifting device; the slot cover 4 has ear plates at its four corners; the slot cover lifting device includes straight connecting rods 7 and 8 hinged to the ear plates at the four corners of the slot cover 4, a sliding rod 12 connecting two straight connecting rods 7 and 8 on one side, and an outer frame. The straight connecting rods are hinged to the sliding rods they are connected to. The outer frame is symmetrically provided with two guide rails 11 and two arc-shaped guide surfaces 13. The sliding rods 12 on both sides are located in the two guide rails 11 respectively. The outer side of the straight connecting rod at the arc-shaped guide surface 13 has a cylindrical protrusion that cooperates with the arc-shaped guide surface 13. When the slot cover 4 is pushed, the sliding rod 12 slides in the guide rail 11, constraining the ends of the straight connecting rods 7 and 8 to be located in the same horizontal plane. Under the constraint of the arc-shaped guide surface 13, the cylindrical protrusion drives the entire slot cover 4 to be lifted through the linkage of the straight connecting rods 7 and 8.

[0017] The present invention, by adopting the above technical solution, has the following beneficial effects: (1) Excellent safety and environmental protection: It abandons the high-risk hydrofluoric acid and its fluorides, adopts an alkaline etching system, and selects safe and non-toxic reagents, which greatly reduces the toxicity, corrosiveness and environmental hazards of the process, and significantly reduces the difficulty and cost of wastewater treatment.

[0018] (2) Low temperature, high efficiency and energy saving: Through the optimized composite formula, high efficiency etching is achieved at room temperature of 20-30℃. The etching rate can reach more than 60% of the traditional high temperature (usually >70℃) alkaline etching process. At the same time, the selectivity (the ratio of the etching rate of the modified area to the unmodified area) is greater than 100:1. The energy consumption of heating and heat preservation is eliminated, and the process cost is reduced.

[0019] (3) Excellent deep hole cleanliness: The chelation-dispersion system in the formula chemically inhibits the generation and adhesion of deposits; the directional alternating waves generated by the special auxiliary equipment physically strip and remove the deposits; the two work together to ensure that even for through holes with a depth-to-width ratio greater than 10:1, the inner wall remains smooth and unblocked.

[0020] (4) High process consistency and reliability: The buffer system stabilizes the etching process; the directional wave washing equipment provides a uniform hydrodynamic environment for each glass plate in the array, avoiding the problem of uneven etching caused by different positions, which is particularly suitable for large-scale production.

[0021] (5) High system integration: This invention provides a complete solution from chemical formulation to physical equipment. The two are designed in synergy to address the challenges of room temperature etching and deep hole cleaning, solving the key obstacles when scaling up laboratory technology to the production line. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a special equipment for double-sided rinsing of etching solution provided in an embodiment of the present invention (the reciprocating structure is shown in an exploded view). Figure 2 This is a schematic diagram of the double-sided wave generator in the special equipment for double-sided rinsing of etching solution provided in the embodiments of the present invention; Figure 3 This is a schematic diagram of the tank cover lifting device in the special equipment for double-sided rinsing of etching solution provided in the embodiment of the present invention. Figure 4 This is a schematic diagram showing the cooperation relationship between the double-sided wave generator and the tank cover lifting device in the special equipment for double-sided rinsing of etching solution provided in the embodiments of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the embodiments of this invention will be described in detail below in non-limiting terms, with reference to the accompanying drawings and examples. Those skilled in the art should understand that the described embodiments are only a part of this invention, and not all of it. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0024] A glass-selective, environmentally friendly etching solution is a water-based alkaline solution. Its core design leverages the synergistic effect of multiple components to simultaneously achieve high etching efficiency, high selectivity, and excellent anti-deposition properties at room temperature. It contains the following components per liter of deionized water: (1) The main etchant is potassium hydroxide at a concentration of 3.0–4.0 mol / L. It provides a high concentration of hydroxide ions, which act as nucleophiles to preferentially attack the silicon-oxygen network with a loose structure and reduced bond energy after laser modification, thus driving the selective etching process.

[0025] (2) pH buffer and stabilizer: 0.2–0.5 mol / L potassium carbonate. Potassium carbonate and potassium bicarbonate formed in the system form a buffer pair, which can effectively stabilize the local pH value at the etching reaction interface and prevent pH loss due to OH groups. - The rapid consumption of the material leads to violent fluctuations in the reaction, making the etching process more stable and controllable, and enhancing the consistency of the etched morphology.

[0026] (3) Composite wetting and penetration system, which is designed to significantly reduce the surface tension of the etching solution and ensure its rapid wetting of high aspect ratio micropores, including the following reagents.

[0027] ① Nonionic surfactants, such as APG-0810 (alkyl glycoside 0810) or Tween-20 (polysorbate-20), are added at a rate of 0.1% to 0.2% (by volume). Their molecules adsorb onto the hydrophilic and hydrophobic surfaces of glass, improving wettability.

[0028] ② Short-chain alcohols, such as ethanol or glycerol, are added at a rate of 1% to 3% (by volume). They further reduce surface tension, enhance penetration, and help to remove microbubbles attached to the pore walls.

[0029] The two work together to provide a smooth channel for the continuous transport of etching reactants and products.

[0030] (4) Multi-mechanism scale inhibition and dispersion system. This component is the key to achieving deep hole cleaning at room temperature. It inhibits the formation and adhesion of insoluble substances through chemical action, including the following reagents.

[0031] ① Metal ion chelating agent, added at a concentration of 5–15 mmol / L of disodium ethylenediaminetetraacetate or sodium citrate. Its core function is to strongly chelate Ca ions dissolved from glass or equipment. 2+ Mg 2+ Al 3+ Fe 3+ The metal ions form stable water-soluble complexes, thereby blocking these "scale-forming cations" and preventing them from combining with silicate ions to form insoluble metal silicate precipitates.

[0032] ② Silica gel dispersant and conditioning agent, added at a concentration of 0.02–0.05 mol / L ammonia water. Ammonium ions can react with silicic acid and its oligomers generated during the etching reaction, preventing silica gel particles from agglomerating and redepositing on the pore walls by forming easily soluble ammonium silicate or by electrostatic stabilization mechanisms, thus keeping them in suspension.

[0033] ③ Polymer dispersant: 100–300 ppm of polyepoxysuccinic acid or low molecular weight polyacrylic acid. These green polymers can interfere with the orderly growth of silicate microcrystals through the "lattice distortion effect," causing them to form loose, soft scale. They also enhance the dispersion of colloidal particles through steric hindrance, producing a synergistic scale-inhibiting effect with chelating agents and ammonium salts. Polymer dispersants can effectively prevent the formation of colloidal particles during etching when there are many impurities or microcrystals in the glass; however, when applied to glass with a single composition (such as quartz glass), their effect on promoting the etching effect is not significant, and therefore they can be omitted.

[0034] All reagents involved in the above etching solution are water-soluble, safe, and non-toxic chemicals. After etching is complete, the etching solution can be reused after filtration and replenishment based on the measurement results of each component.

[0035] In addition, this embodiment also provides a special device for alternating wave washing of both sides of a glass plate, which can be used in conjunction with the above-mentioned etching solution.

[0036] This equipment is designed to actively generate highly directional, periodically changing fluid motion to overcome the inherent limitations of low mass transfer efficiency in static immersion or ordinary macroscopic eddies within glass plate arrays. The equipment structure includes a tank, a bidirectional wave generator, and a tank cover lifting device.

[0037] Preferably, the tank is made of stainless steel, with the inner surface and edges covered with polytetrafluoroethylene (PTFE). The tank has a cuboid structure, and the bottom is fixed with elastic clips (PTFE-coated) for vertically clamping and fixing multiple glass substrates, ensuring they are arranged in parallel with a constant spacing and completely immersed in the etching solution. Temperature sensors can be installed inside the tank to monitor the etching temperature, and conductivity or pH sensors can be integrated to monitor the activity of the etching solution. The tank is a fixed device, allowing for the addition of heating devices on the outer bottom or inside the jacket, for heating the entire tank and the etching solution when the ambient temperature deviates significantly from room temperature (20°C) or when precise control of the reaction temperature is required. Additionally, a liquid guide pipe and a filter can be installed at the bottom of the tank for convenient waste discharge and treatment.

[0038] Preferably, the bidirectional wave generator is separately installed from the tank to avoid the need for additional anti-corrosion measures for moving parts and sealing and isolation measures for the drive device when the two are integrated. The waves used for scouring are formed by the reciprocating motion of push plates symmetrically distributed on both sides of the tank. The push plates are made of stainless steel (coated with polytetrafluoroethylene). The protrusion at the top of the push plate passes through the tank cover plate and is connected to the sliding plate in the through-slot on the surface of the tank cover. The sliding plate is connected to the reciprocating structure driven by the motor and slides back and forth on the through-slot with the reciprocating structure. On the one hand, it constrains the linear motion of the reciprocating structure on the tank cover, and on the other hand, it closes the through holes on the cover plate to prevent liquid from splashing out from here when the waves scour back and forth and to prevent the heat of the liquid in the tank from dissipating.

[0039] The bidirectional wave generator is a typical reciprocating structure. Its main body consists of an intermittent gear (incomplete gear) and two parallel racks that mesh with it. These two racks are integrated into a single ring (a graphic consisting of two semicircular rings and two strips connected to the ends of the semicircular rings) through two semicircular rings. The lower end face of the single ring is connected to the sliding plate and forms a linkage. The motor is keyed to the intermittent gear and drives it to rotate. Through the meshing of the incomplete teeth of the intermittent gear with the two parallel racks in one rotation cycle, the rotational motion is converted into the reciprocating linear motion of the single ring.

[0040] The reciprocating linear motion of the ring drives the linkage between the slider and the two push plates that penetrate the liquid. When one push plate advances towards the glass plate array, it pushes the etching solution to generate a planar "wave". This liquid flow vertically washes the front of the glass plate and all the through-hole inlets, pushing the consumed old reaction liquid and the by-products that have been loosened and peeled off by the chemical dispersant to the other side of the array. Then, the side push plate retracts, while the side push plate advances synchronously, generating a reverse scouring.

[0041] Waves are mechanical waves, and their basic characteristic is that they can continue to propagate around obstacles. Therefore, the blocking effect of the front glass panel in the glass array is limited. The reciprocating waves form a strong, directional and periodically changing fluid scouring in the narrow gaps between the closely arranged glass panels. Compared to ultrasonic-assisted etching, this mechanical wave has a more uniform energy distribution, allowing it to act on both sides of each glass plate and all through-holes in the array with minimal attenuation, without causing a significant increase in the overall temperature of the etching solution. Compared to traditional mechanical stirring, this directional wave can directly penetrate the gaps between the plates, producing equally effective direct scouring on both sides of the glass plate, avoiding the cleaning dead zones on the back side of the plate caused by macroscopic eddy current "flow around"; compared to nitrogen bubbling technology, this mechanical wave provides a stronger and more directional shearing force, making it particularly suitable for scenarios where the etching solution needs to be rapidly updated in holes with high aspect ratios.

[0042] Preferably, the slot cover lifting device is designed to facilitate the removal of the slot cover for placing (or removing) glass plates and adding etching liquid; four ear plates are distributed at the four corners of the slot cover, each ear plate is connected to a straight connecting rod by a pin, and the ends of two of the straight connecting rods are provided with cylindrical protrusions that extend into a guide plate with an arc-shaped guide groove; the other ends of the two straight connecting rods on the same side of the four straight connecting rods are respectively connected to the two ends of a slide rod (with cylindrical protrusions); the slide rod is located in a U-shaped guide rail, and the sliding of the slide rod in the guide rail causes the slot cover to slide accordingly, and the cylindrical protrusions of the corresponding ear plates also move on the arc surface, thereby driving the lifting and lowering of the slot cover.

[0043] The specialized equipment provided by this invention, when used in conjunction with an etching solution, forms a highly efficient synergy between "chemical dispersion" and "physical scouring." The scale-inhibiting and dispersing system in the formula chemically prevents the formation and adhesion of hard deposits, while the directional alternating waves provide a directional driving force for the movement of loose particles. The combination of these two elements achieves a radical removal of byproducts from deep pores.

[0044] Here are more specific examples: Example 1: A method for preparing a selective and environmentally friendly glass etching solution Taking the preparation of a 1-liter working solution suitable for etching laser-modified borosilicate glass at room temperature as an example, the preparation steps are as follows: Preparation and precooling: Add approximately 700 ml of deionized water to a strong alkali-resistant container made of polypropylene or polytetrafluoroethylene. Precool the container in an ice-water bath to prepare for the heat generated during the subsequent dissolution of the alkali metal hydroxide.

[0045] Dissolving the main etchant and buffer: Under continuous and gentle mechanical stirring (avoid vigorous stirring to prevent the introduction of excessive air bubbles), slowly add 224g of potassium hydroxide (analytical grade, purity ≥85%) and 69g of anhydrous potassium carbonate (analytical grade) to cooled deionized water. Add the materials slowly and stir continuously until the solids are completely dissolved. This process is an exothermic reaction, and the solution temperature must be controlled to not exceed 40℃.

[0046] Add chelating agent and dispersant: Add 0.56g of disodium ethylenediaminetetraacetate (analytical grade) and 1.5ml of ammonia water with a concentration of 25-28% (analytical grade) to the above transparent alkaline solution in sequence.

[0047] Add wetting and penetrating agents: Continue stirring, then add 20 ml of ethanol (analytical grade) and 1.5 ml of nonionic surfactant Tween-20 in sequence.

[0048] Volume adjustment and homogenization: Add deionized water to bring the solution volume to 1L, and continue stirring for about 15 minutes to ensure all components are thoroughly mixed to obtain a clear and transparent etching solution. The pH value of this etching solution is greater than 13 at 25°C. After preparation, allow it to stand to defoam, and store it in a sealed, light-protected container at room temperature for later use.

[0049] Example 2: A specific implementation of a dedicated etching solution equipment refer to Figure 1 , Figure 2 , Figure 3 This embodiment describes in detail a preferred structure of a dedicated etching solution device.

[0050] like Figure 1 As shown, the main body of tank 1 is welded from stainless steel. To enhance corrosion resistance, the inner wall of the tank and all metal parts in contact with the etching solution are lined with 2mm thick polytetrafluoroethylene (PTFE). The bottom of the tank has a drain port with a valve, connected to an external filtration and circulation system (not shown in the figure), enabling online filtration and reuse of the etching solution. Various sensors (not shown in the figure) are integrated on the sides of the tank. An array of elastic clips 2 (PTFE-coated) is fixed to the bottom of the tank for vertically clamping and fixing multiple glass plates. Two push plates 3, made of stainless steel (PTFE-coated), extend into tank 1. The protrusions at the top of the push plates pass through the rectangular opening of the tank cover 4 and are connected to the sliding plate 5 and the "one-ring" (a graphic composed of two rings and two rectangular bars, similar to a standard running track) 6 via bolts. Parallel racks are present on the inner side of the straight edge of the "one-ring". The ear plates distributed at the four corners of the tank cover 4 are connected to the straight connecting rods 7 and 8 via pins.

[0051] like Figure 2 As shown, the slider 5 can be embedded in the straight groove on the surface of the slot cover 4 and can slide therein, while the "circular ring" 6 can be inserted into the space of the L-shaped guide rails on both sides of the slot cover 4 and slide under the constraint of the guide rails; since the push plate 3, the slider 5 and the "circular ring" 6 are fixed to each other by bolts, the reciprocating motion of the "circular ring" 6 can cause the slider 5 and the push plate 3 to move together.

[0052] The core of the double-sided wave generator is an intermittent gear 10 driven by a motor 9 (connected to the motor key). In the first half of the rotation cycle, the teeth of the intermittent gear 10 mesh with the parallel rack on one straight edge of the "one-round ring" 6, thereby driving the "one-round ring" 6, the rigidly connected slider 5, and the push plate 3 to move linearly in one direction. In the second half of the rotation cycle, the intermittent gear 10 disengages from the previous parallel rack and meshes with the parallel rack on the other side, thus causing the "one-round ring" 6 to move linearly in the opposite direction. In this way, the continuous rotation of the intermittent gear 10 is converted into the periodic reciprocating linear motion of the "one-round ring" 6, the slider 5, and the push plate 3. The alternating advance and retraction of the push plate 3 causes the etching liquid in the tank 1 to be periodically washed by waves in both directions. The slider 5 slides in the straight groove on the surface of the tank cover 4, which can also cover the rectangular opening on the tank cover 4, thus sealing it and preventing liquid from splashing out.

[0053] like Figure 3 As shown, a slide rod 12 is embedded in the U-shaped guide rail 11. Each end of the slide rod 12 has a cylindrical protrusion and is connected to one end of the straight connecting rod 7 and the straight connecting rod 8 through hole. The other end of the straight connecting rod 7 is a round through hole, while the other end of the straight connecting rod 8 is a round blind hole (the end with the cylindrical protrusion). The ear plates at the four corners of the tank cover 4 are connected to the ends of the straight connecting rod 7 and the straight connecting rod 8 respectively by pins. The cylindrical protrusion in the straight connecting rod 8 is pressed on the arc surface of the arc-shaped guide plate 13. The arc-shaped guide plate 13 is fastened to the U-shaped guide rail 11 by bolts. When the slide rod 12 is pulled to slide horizontally along the U-shaped guide rail 11, the tank cover 4 can simultaneously achieve a compound movement of "horizontal movement away" and "vertical descent / ascent" through the traction of the straight connecting rods 7 and 8, and the constraint movement of the cylindrical protrusion in the straight connecting rod 8 on the arc surface of the arc-shaped guide plate 13, thereby completely freeing up the space above the tank, facilitating the removal and placement of the substrate, the addition of liquid, and the maintenance of the tank.

[0054] Example 3: Glass through-hole etching process using specialized double-sided rinsing equipment This embodiment demonstrates the complete process of etching a laser-modified glass plate using the etching solution prepared in Example 1 and the special equipment in Example 2.

[0055] The glass plates are vertically inserted into the slots of the elastic clips 2, ensuring that the glass plates are parallel to each other; sufficient amount of the etching solution prepared in Example 1 is injected into the tank 1 to ensure that the liquid surface completely submerges all the glass plates.

[0056] Start the motor and set the movement cycle of the intermittent gear 10 to 30s (that is, it takes 30s for each pusher plate to complete one "push-retract" cycle). After that, the pusher plates 3 on both sides move alternately according to the set pattern, generating periodic reversing planar waves on both sides of the glass plate array, which strongly scour both sides of the glass plate and the through holes. The etching process lasts for 180 minutes.

[0057] After etching is complete, turn off the equipment, raise the tank cover, remove the glass plate and immediately immerse it in a large amount of flowing deionized water for rinsing. Then place it in a gentle ultrasonic cleaner and clean it with deionized water for 5 minutes. Finally, blow it dry with high-purity nitrogen.

[0058] Microscopic observation of the etching results showed that the laser-modified area was completely etched through, the hole walls were smooth and the outline was clear, and the unmodified glass surface remained smooth. By measuring the etching time of the modified area and the thickness loss of the unmodified area, the etching selectivity ratio was calculated to be greater than 150:1. No particles or gel-like deposits were found to block the through-hole or the glass surface.

[0059] Comparison of proportions and effects To highlight the comprehensive advantages of the present invention, the following comparative experiments were conducted, and all experiments used the same batch of laser-modified glass substrates.

[0060] Comparative Example 1 (Traditional High-Temperature KOH Etching): A 4.0 mol / L pure KOH solution was used as the etching solution, and the glass was etched by static immersion in a 75°C constant-temperature water bath. After 120 minutes, the glass was etched through, but microscopic observation showed that the hole walls were obviously wavy and rough, and the unmodified surface was severely hazy. The selectivity ratio was estimated to be only 25:1.

[0061] Comparative Example 2 (without auxiliary double-sided rinsing): Static immersion etching was performed at 25°C using the exact same etching solution as in Example 1. After 300 minutes, the etching had not completely penetrated, and the pores were filled with white, opaque silicate gel deposits, completely blocking the channels.

[0062] Comparing the results of Example 3 with all comparative examples fully demonstrates the necessity and superior effectiveness of the synergistic operation of the "selective environmentally friendly etching solution" and the "double-sided wave-flushing special equipment" proposed in this invention. This overall solution successfully achieves safe, environmentally friendly, low-temperature, efficient, uniform, and deep-hole-cleaning selective etching of glass, possessing significant industrial application value.

[0063] In summary, the etching solution of this invention is a completely hydrofluoric acid-free, water-based alkaline solution containing potassium hydroxide, potassium carbonate, a composite wetting and penetrating agent, and a multi-mechanism scale inhibitor and dispersant. It can achieve efficient and highly selective etching of laser-modified areas of glass at room temperature (around 20°C) and effectively inhibit by-product deposition. The dedicated equipment of this invention features a double-sided alternating wave-flushing structure. Through the alternating reciprocating motion of symmetrically arranged push plates, a strongly directional and periodically changing liquid flow is generated on both sides of the glass plate array, achieving efficient flushing and mass transfer renewal of both sides of the glass plate and the interior of the through-holes. This invention combines an environmentally friendly etching solution with a dedicated physical flushing device, forming a highly efficient synergy between chemical dispersion and physical flushing. It solves the problems of high temperature, high toxicity, easy clogging of deep holes, and poor uniformity in traditional processes, providing a complete solution for the green, low-cost, and large-scale production of glass through-hole technology.

[0064] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A selective environmentally friendly etching solution for glass, characterized in that, This is a water-based alkaline solution, containing the following components per liter: a) Main etchant: 3.0–4.0 mol / L potassium hydroxide; b) pH buffer and stabilizer: 0.2–0.5 mol / L potassium carbonate; c) A composite wetting and penetration system comprising: 0.1% to 0.2% by volume of a nonionic surfactant and 1% to 3% by volume of a short-chain alcohol; d) A multi-mechanism scale inhibition and dispersion system, comprising: 5–15 mmol / L of metal ion chelating agent and 0.02–0.05 mol / L of ammonia.

2. The glass selective environmentally friendly etching solution according to claim 1, characterized in that, The nonionic surfactant is either APG-0810 or Tween-20.

3. The glass selective environmentally friendly etching solution according to claim 1, characterized in that, The short-chain alcohol is ethanol or glycerol.

4. The glass selective environmentally friendly etching solution according to claim 1, characterized in that, The metal ion chelating agent is disodium ethylenediaminetetraacetate or sodium citrate.

5. The glass selective environmentally friendly etching solution according to claim 1, characterized in that, The multi-mechanism scale inhibitor and dispersion system also contains 100-300 ppm of a polymeric dispersant, which is polyepoxysuccinic acid or low molecular weight polyacrylic acid.

6. A special double-sided alternating wave-flushing device for use with the etching solution according to any one of claims 1 to 5, characterized in that, include: The tank (1) is used to hold the etching solution; The groove cover (4) is placed on the groove body (1), with a straight groove in the center and hollow sections at both ends of the straight groove; A substrate fixing array is set in the groove (1) for vertically clamping multiple glass substrates arranged in parallel. A bidirectional wave generator is used to drive two push plates (3) symmetrically arranged on both sides of the substrate fixing array to perform alternating reciprocating linear motion, so as to generate periodically reversed directional liquid flow in the etching solution to scour both sides of the glass substrate.

7. The special equipment for double-sided alternating wave scouring as described in claim 6, characterized in that, The bidirectional wave generator includes a drive motor (9), an intermittent gear (10) driven by the drive motor (9), and a ring (6) with two parallel racks on its inner side; the intermittent gear (10) alternately meshes with the two parallel racks in one rotation cycle, converting the continuous rotational motion of the motor into the reciprocating linear motion of the ring (6); the ring (6) is connected to two push plates (3) through a slider (5) to drive the synchronous reciprocating motion of the push plates (3).

8. The special equipment for double-sided alternating wave scouring as described in claim 7, characterized in that, The sliding piece (5) is embedded in the straight groove of the groove cover (4) and can slide along the straight groove. The push plate (3) is connected to the sliding piece (5) through the hollow sections at both ends of the straight groove. The sliding piece (5) seals the hollow sections at both ends of the straight groove to prevent liquid from splashing out.

9. The special equipment for double-sided alternating wave scouring as described in claim 6, characterized in that, It also includes a trough cover lifting device; the trough cover (4) has ear plates at its four corners; the trough cover lifting device includes straight connecting rods (7, 8) hinged to the ear plates at the four corners of the trough cover (4), sliding rods (12) connecting two straight connecting rods (7, 8) on one side, and an outer frame. The straight connecting rods are hinged to the sliding rods they are connected to. The outer frame is symmetrically provided with two guide rails (11) and two arc-shaped guide surfaces (13). The sliding rods (12) on both sides are located in the two guide rails (11) respectively. The outer side of the straight connecting rod at the arc-shaped guide surface (13) has a cylindrical protrusion that cooperates with the arc-shaped guide surface (13). When the trough cover (4) is pushed, the sliding rods (12) slide in the guide rails (11), constraining the ends of the straight connecting rods (7, 8) to be located in the same horizontal plane. Under the constraint of the arc-shaped guide surface (13), the cylindrical protrusion drives the entire trough cover (4) to be lifted through the linkage of the straight connecting rods (7, 8).

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