Method for removing adhesive from circuit board recycled materials

Abstract

The invention provides a glue removing method for a recycled material of a circuit board. The glue removing method for the recycled material of the circuit board comprises the following steps that the circuit board is put into a bulking groove to be softened and expanded and then is washed with water; putting the washed circuit board into a degumming tank, and adding potassium permanganate degumming liquid for degumming; the circuit board is moved into a glue removal liquid recovery tank to be washed, and glue removal liquid washing liquid is collected; conveying the glue-removing washing liquid to a glue-removing tank for liquid supplementing, and adding clear water into a glue-removing liquid recovery tank for dilution; putting the degummed circuit board into a pre-neutralization tank for pre-neutralization; putting the pre-neutralized circuit board into a neutralizing tank for neutralizing; and washing the neutralized circuit board with water. The glue-removing washing liquid is conveyed into the glue-removing tank, potassium permanganate is recycled, discharge of the glue-removing washing liquid is reduced, the glue-removing washing liquid is diluted to clean the circuit board, residual potassium permanganate on the circuit board is reduced, and subsequent use of a pre-neutralizer solution is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit board manufacturing, and in particular to a method for removing glue from recycled and reused materials of circuit boards. Background Art

[0002] After drilling holes in the circuit board, vertical copper deposition, horizontal copper deposition, (horizontal line) black hole / black shadow and other processes are used to connect the wires between the layers of the double-sided or multi-layer circuit board, providing conductivity for the subsequent electroplating copper. Before this process, a degumming process is carried out, which is used to roughen the hole wall and remove the glue residue that will cause the inner layer circuit to fail to conduct electricity.

[0003] Potassium permanganate degumming utilizes the strong oxidizing property of potassium permanganate to react chemically with the resin under high temperature and strong alkali conditions, thereby achieving the purpose of dissolving and removing the glue residue. This method can effectively remove the glue residue, so that the hole wall forms an ideal microscopic roughness, and the consumed potassium permanganate can be regenerated by electrolysis. It is a relatively stable, economical and practical degumming method. However, a lot of wastewater is generated in the production of circuit boards, and the cost of treating strong acid and strong alkali wastewater is high. Therefore, recycling potassium permanganate for utilization can reduce wastewater discharge and treatment costs, while reducing production costs.

[0004] For example, the circuit board desmear recycling treatment system disclosed in the comparative document CN201511002284.9 includes an outer water bucket, an inner filter bucket, a filter pump and a drug washing pump; the outer water bucket is connected with a water bucket exhaust pipe, a water bucket air pressure pipe, a water bucket water supply pipe, a first cleaning pipe and a second cleaning pipe; an isolation filter membrane is arranged in the inner filter bucket, and the inner filter bucket is connected with a water production pipe, a drainage pipe, a drug washing water supply pipe, a filter bucket exhaust pipe and a filter bucket air pressure pipe. This scheme effectively reduces the centipoise value in the solution by efficiently intercepting and isolating all solid particles in the potassium permanganate solution, making the solution flow permeable without blocking holes, and reducing the amount of potassium permanganate solution carried out of the substrate in a fast film bursting time, greatly improving the desmear efficiency, but this scheme does not solve the wastewater generated by subsequent cleaning of the circuit board, and utilizes the potassium permanganate of the wastewater to reduce sewage discharge and treatment costs.

[0005] For example, the comparative document CN201911043646.7 discloses a method for extending the service life of a PCB degumming tank, comprising the following steps: S1: discharging the degumming tank liquid and storing it, and cleaning the evacuated potassium permanganate tank; S2: adding sulfuric acid and hydrogen peroxide to the potassium permanganate tank, so that the volume of sulfuric acid in the potassium permanganate tank accounts for 0.5%-5%, and the volume of hydrogen peroxide accounts for 1%-6%; S3: draining the potassium permanganate tank and then rinsing it with water; S4: drawing the stored degumming tank liquid back into the potassium permanganate tank; after step S4, heating, circulating, inflating, and regenerating the potassium permanganate tank, and then replenishing the liquid level. When the temperature rises to the working temperature, potassium permanganate is added to check the degumming rate. This solution reduces the frequency of tank replacement by cleaning the potassium permanganate tank, thereby saving potassium permanganate usage and reducing the difficulty of wastewater treatment. However, this solution solves the wastewater generated by subsequent cleaning of circuit boards and utilizes the potassium permanganate in the wastewater, reducing wastewater discharge and treatment costs. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for removing glue from recycled and reused materials of circuit boards, which can recover potassium permanganate for reuse, reduce direct discharge of degumming water washing liquid, and reduce potassium permanganate residue on circuit boards.

[0007] The purpose of this disclosure is achieved through the following technical solutions:

[0008] A method for removing glue from recycled materials of a circuit board, comprising the following steps:

[0009] Put the circuit board into a swelling tank, add a swelling agent solution, and heat it to soften and expand it;

[0010] Washing the softened and expanded circuit board with water;

[0011] Put the washed circuit board into a degumming tank, add potassium permanganate degumming solution and heat to remove the glue;

[0012] The debonded circuit board is moved into a debonding liquid recovery tank for water washing, wherein the debonding liquid recovery tank stores debonding water washing liquid;

[0013] The degumming liquid in the degumming liquid recovery tank is transported to the degumming tank to replenish the potassium permanganate degumming liquid in the degumming tank, and clean water is added to the degumming liquid recovery tank to dilute the degumming liquid in the degumming liquid recovery tank;

[0014] Putting the circuit board after debonding into a pre-neutralization tank, adding a pre-neutralizer solution for pre-neutralization;

[0015] Putting the pre-neutralized circuit board into a neutralization tank, and adding a neutralizer solution for neutralization;

[0016] The neutralized circuit board is washed with water to obtain a circuit board.

[0017] In one of the embodiments, the concentration of potassium permanganate after dilution of the degumming water washing solution in the degumming solution recovery tank is less than 5 g / L.

[0018] In one of the embodiments, the temperature of the potassium permanganate degumming solution in the degumming tank is 70° C.-85° C., and the degumming time of the circuit board is 10 min-15 min.

[0019] In one embodiment, before placing the pre-neutralized circuit board in a neutralization tank and adding a neutralizer solution for neutralization, placing the circuit board after debonding in a pre-neutralization tank and adding a pre-neutralizer solution for pre-neutralization, the following steps are also included:

[0020] The pre-neutralized circuit board is washed with water.

[0021] In one embodiment, the pre-neutralizer solution includes H2SO4 and H2O2, the volume percentage concentration of H2SO4 is 1%-2%, and the volume percentage concentration of H2O2 is 1%-2%; and / or,

[0022] The neutralizer solution includes reducing organic acid and H2SO4, the volume percentage concentration of the reducing organic acid is 18%-25%, and the volume percentage concentration of the H2SO4 is 4%-6%.

[0023] In one embodiment, after placing the circuit board in the neutralization tank and adding a neutralizer solution for neutralization, the neutralized circuit board is washed with water to obtain the circuit board, and the following steps are also included:

[0024] The low-concentration neutralizer solution after the neutralization reaction is transported to the pre-neutralization tank to replace the pre-neutralizer solution.

[0025] In one embodiment, the temperature of the pre-neutralizer solution in the pre-neutralizer tank is 25° C.-32° C., and the reaction time of the circuit board in the pre-neutralizer solution is 1 min-3 min.

[0026] In one embodiment, the temperature of the neutralizer solution in the neutralization tank is 38° C.-42° C., and the reaction time of the circuit board in the neutralizer solution is 3 min-5 min.

[0027] In one embodiment, the temperature of the leavening agent solution in the leavening tank is 70°C-80°C.

[0028] In one embodiment, after washing the puffed circuit board, placing the washed circuit board in a degumming tank, adding potassium permanganate degumming solution and heating it before degumming, the following steps are also included:

[0029] The expanded circuit board is moved into an expansion recovery tank for water washing, wherein the expansion recovery tank stores a water washing liquid of an expansion agent;

[0030] The leavening agent water washing liquid of the leavening recovery tank is transported to the leavening tank to replenish the leavening agent solution.

[0031] Compared with the prior art, the present invention has at least the following advantages:

[0032] The above-mentioned degumming method for recycling and reusing materials of circuit boards moves the degumming circuit boards into a degumming liquid recovery tank for water washing, and the degumming water washing liquid collected by the degumming liquid recovery tank is transported to the degumming tank, thereby avoiding direct discharge and treatment of the degumming water washing liquid. By consuming the degumming water washing liquid, the potassium permanganate of the degumming water washing liquid is recycled and reused, and the production cost of the degumming method is reduced;

[0033] The potassium permanganate of the degumming solution in the degumming solution recovery tank is diluted with clean water, so that the degumming solution is kept at a low concentration to clean the circuit board, reducing the residual potassium permanganate on the circuit board, thereby reducing the use of subsequent pre-neutralizer solution, thereby extending the service life of the pre-neutralizer solution and reducing production costs.

[0034] The pre-neutralization cylinder is replenished with a low-concentration neutralizer solution after the reaction, and the neutralizer solution after the neutralization reaction is transported to the pre-neutralization tank to replace the pre-neutralizer solution, so that the neutralizer solution can be further utilized. The consumption of the neutralizer solution reduces the discharge treatment of the neutralizer solution, thereby reducing the production cost. The high-concentration neutralizer solution is used to replace the pre-neutralizer solution for pre-neutralization, which also extends the service life of the pre-neutralizer solution in the pre-neutralization cylinder, thereby saving production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 A flowchart of the steps of a method for removing glue from recycled and reused circuit board materials according to an embodiment;

[0037] Figure 2It is a structural schematic diagram of a degumming liquid recovery tank and a degumming tank conveying system according to an embodiment;

[0038] Figure 3 for Figure 2 Another structural schematic diagram of the degumming liquid recovery tank and the degumming tank transportation is shown. DETAILED DESCRIPTION

[0039] In order to facilitate the understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are given in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thoroughly and comprehensively understood.

[0040] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present disclosure. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0042] In order to better understand the technical solutions and beneficial effects of the present invention, the present invention is further described in detail below in conjunction with specific embodiments:

[0043] The present invention relates to a degumming method for recycling and reusing materials of a circuit board. In one embodiment, the method comprises the following steps: placing the circuit board in a bulking tank, adding a bulking agent solution to heat the circuit board for softening and expansion; washing the softened and expanded circuit board with water; placing the washed circuit board in a degumming tank, adding potassium permanganate degumming solution to heat the circuit board for degumming; moving the degummed circuit board into a degumming liquid recovery tank for water washing, wherein the degumming liquid recovery tank stores degumming water washing liquid; conveying the degumming water washing liquid in the degumming liquid recovery tank to the degumming tank to replenish the potassium permanganate degumming liquid in the degumming tank, adding clean water to the degumming liquid recovery tank to dilute the degumming water washing liquid in the degumming liquid recovery tank; placing the degummed circuit board in a pre-neutralization tank, adding a pre-neutralizer solution for pre-neutralization; placing the pre-neutralized circuit board in a neutralization tank, adding a neutralizer solution for neutralization; washing the circuit board with water to obtain a circuit board.

[0044] See also Figure 1 , which is a method for removing glue from recycled and reused circuit board materials according to an embodiment of the present invention, comprising the following steps:

[0045] S101: Put the circuit board into the expansion tank, add the expansion agent solution, heat it to soften and expand it. In this embodiment, the expansion agent solution can remove the debris and pollutants of the circuit board, soften the glue residue on the hole wall of the circuit board through the expansion agent, expand the expansion agent and penetrate into the cross-linked part after the resin is polymerized, so that the long chain of the resin molecular structure is cracked, thereby facilitating the dissolution of the resin.

[0046] S103: Wash the softened and expanded circuit board with water. In this embodiment, washing with water can remove the leavening agent, resin fragments, glue and other residues remaining on the surface of the circuit board during the swelling process. The residues may block the filtration system in the degumming tank, resulting in poor circulation of the degumming liquid, thereby affecting the degumming efficiency; secondly, some components in the residues may react with the degumming liquid to produce by-products that are not conducive to degumming, further reducing the degumming effect. The surface cleanliness of the circuit board is maintained by washing with water, thereby facilitating the subsequent degumming steps.

[0047] S105: Put the washed circuit board into a degumming tank, add potassium permanganate degumming solution, and heat it to remove the glue. In this embodiment, the potassium permanganate degumming solution includes potassium permanganate and sodium hydroxide. Potassium permanganate has strong oxidizing properties and reacts chemically with resin under high temperature and strong alkali conditions. The generated potassium manganate will contaminate the potassium permanganate degumming solution, thereby reducing the service life of the potassium permanganate degumming solution. Therefore, a regeneration device is provided in the degumming tank, and the potassium permanganate degumming solution is electrolyzed by the regeneration device, so that manganate radicals are oxidized and regenerated into useful permanganate ions, thereby increasing the service life of the potassium permanganate degumming solution.

[0048] S107 moves the debonded circuit board into a debonding liquid recovery tank for water washing, wherein the debonding liquid recovery tank stores debonding water washing liquid. In this embodiment, the circuit board can be washed by spraying and immersion in turn to remove the potassium permanganate debonding liquid remaining on the surface of the circuit board, thereby reducing the amount of the potassium permanganate debonding liquid remaining on the circuit board and reducing the use of the subsequent neutralizing agent.

[0049] S109: transporting the degumming water washing liquid from the degumming liquid recovery tank to the degumming tank to replenish the potassium permanganate degumming liquid in the degumming tank, and adding clean water to the degumming liquid recovery tank to dilute the degumming water washing liquid in the degumming liquid recovery tank. In the present embodiment, when degumming is performed after adding potassium permanganate degumming liquid and heating it, the water in the degumming tank will continue to evaporate, and the degumming water washing liquid in the degumming liquid recovery tank is transported to the degumming tank by a delivery pump, which can replenish the liquid level of potassium permanganate degumming liquid in the degumming tank, and also enable the degumming water washing liquid to be further utilized, thereby reducing the discharge of the degumming water washing liquid and improving the utilization of potassium permanganate, thereby reducing the production cost; when the degumming water washing liquid in the degumming liquid recovery tank is transported to the degumming tank, the liquid level of the degumming water washing liquid is reduced, and the degumming water washing liquid in the degumming liquid recovery tank is supplemented and diluted with clean water, so that the degumming water washing liquid maintains a low potassium permanganate concentration, so that after the circuit board is washed with the degumming water washing liquid, the amount of potassium permanganate remaining on the circuit board is less, further reducing the amount of subsequent neutralizer.

[0050] It is understandable that when adding potassium permanganate degumming liquid and heating it for degumming, the amount of water evaporated is the amount that needs to be replenished in the degumming tank. Specifically, when the potassium permanganate degumming liquid in the degumming tank has been heated for a preset time, the liquid level of the degumming liquid recovery tank is reduced; the degumming water washing liquid in the degumming liquid recovery tank is delivered to the degumming tank by a delivery pump, and the delivery amount and delivery time of the delivery pump are controlled so that the degumming water washing liquid fills the liquid level of the degumming liquid recovery tank.

[0051] S111: placing the circuit board after the debonding into a pre-neutralization tank, adding a pre-neutralizer solution for pre-neutralization. In this embodiment, the pre-neutralizer solution can react with permanganic acid under acidic conditions, and the pre-neutralization can remove most of the potassium permanganate on the circuit board, thereby reducing the residual potassium permanganate on the circuit board.

[0052] S113 puts the pre-neutralized circuit board into a neutralization tank and adds a neutralizer solution for neutralization. In this embodiment, the residual potassium permanganate may cause quality problems in the circuit board, such as poor hole wall bonding, no copper in the hole, hole wall detachment, blown holes, and exploded holes. The neutralizer solution can react with permanganic acid under acidic conditions, and further react with the circuit board through secondary neutralization, so that the residual potassium permanganate in the circuit board is further removed. The quality risks caused by the residual potassium permanganate are avoided through pre-neutralization and secondary neutralization.

[0053] S115: washing the neutralized circuit board with water to obtain the circuit board. In this embodiment, after the circuit board is washed with water, the residual neutralizer solution on the circuit board is removed, thereby maintaining the cleanliness of the circuit board.

[0054] The above-mentioned degumming method for recycling and reusing materials of circuit boards moves the circuit boards after degumming into a degumming liquid recovery tank for water washing, and the degumming water washing liquid collected in the degumming liquid recovery tank is transported to the degumming tank, thereby avoiding direct discharge and treatment of the degumming water washing liquid, and consuming the degumming water washing liquid, recycling and reusing the potassium permanganate of the degumming water washing liquid, and reducing the production cost of the degumming method; the potassium permanganate of the degumming water washing liquid in the degumming liquid recovery tank is diluted with clean water, so that the degumming water washing liquid maintains a low concentration for cleaning the circuit boards, reducing the residual potassium permanganate of the circuit boards, thereby reducing the use of subsequent pre-neutralizer solution, thereby extending the service life of the pre-neutralizer solution, and further reducing the production cost.

[0055] In one of the embodiments, the potassium permanganate concentration of the degumming water washing solution in the degumming liquid recovery tank after dilution is less than 5g / L. In this embodiment, the potassium permanganate concentration of the degumming water washing solution is diluted to less than 5g / L, so that the degumming water washing solution can be used to wash the circuit board multiple times, so that the potassium permanganate remaining in the circuit board after washing is maintained at a low concentration, thereby reducing the consumption of the pre-neutralizer solution in the subsequent pre-neutralization process.

[0056] Further, in one embodiment, the degumming water washing liquid includes the amount of potassium permanganate and water brought into the circuit board, and the number of times the degumming water washing liquid cleans the circuit board can be analyzed to obtain the preset number of times the degumming water washing liquid cleans the circuit board, and then the degumming water washing liquid in the degumming water recovery tank is diluted, specifically, including the following steps:

[0057] When the volume of the liquid in the degumming liquid recovery tank is fixed, the concentration change of potassium permanganate in the degumming liquid after each water washing can be obtained by sampling and testing;

[0058] When the concentration of potassium permanganate is greater than the preset concentration of potassium permanganate, the preset number of times of cleaning the circuit board is obtained by analysis;

[0059] When the number of cleaning times for the circuit board reaches half of the preset number, sampling is performed to detect the concentration of potassium permanganate;

[0060] Check whether the concentration of potassium permanganate is greater than or equal to 0.5 times the preset concentration of potassium permanganate, and pre-fill the degumming liquid recovery tank with water to dilute the potassium permanganate concentration to 8g / L-9g / L.

[0061] In this embodiment, the preset number of times of cleaning the circuit board is obtained through detection and analysis, so that the concentration of potassium permanganate in the degumming water washing solution can be controlled in time during the production process, thereby reducing the number of times the degumming water washing solution is diluted with water, thereby improving production efficiency; specifically, the preset concentration of potassium permanganate is 18g / L-20g / L, and when the number of cleaning times reaches half of the preset number of times, when the concentration of potassium permanganate is greater than or equal to 0.5 times the preset concentration of potassium permanganate, a pre-water replenishment operation is performed through the degumming liquid recovery tank. Since the potassium permanganate in the degumming liquid recovery tank is diluted by the pre-water replenishment operation during the cleaning process, the concentration of potassium permanganate is reduced to 8g / L-9g / L, ensuring that when the circuit board reaches the preset number of cleaning times, the concentration of potassium permanganate in the degumming liquid recovery tank is less than 5g / L, so that the amount of potassium permanganate brought out by the circuit board is less, thereby reducing the subsequent consumption of the pre-neutralizer solution.

[0062] Furthermore, the step of detecting whether the concentration of potassium permanganate is greater than or equal to 0.5 times the preset concentration of potassium permanganate and pre-filling the degumming liquid recovery tank with water further includes the following steps:

[0063] Collect the water dilution level of the degumming liquid recovery tank;

[0064] Check whether the water dilution level is greater than or equal to the warning dilution level;

[0065] If the water dilution level is greater than or equal to the warning dilution level, start the delivery pump to deliver the degumming water washing liquid to the degumming liquid recovery tank, and the delivery time is controlled within 2S-3S.

[0066] In this embodiment, when the degumming liquid recovery tank is replenished with water, adding too much water will cause the degumming water washing liquid to overflow the degumming liquid recovery tank. The liquid level of the degumming liquid recovery tank is detected by a liquid level sensor. When the liquid level of the degumming liquid recovery tank reaches the warning dilution level, the delivery pump is turned on to pump out the degumming water washing liquid in time; the delivery time of the delivery pump is short, so that when the liquid level of the degumming water washing liquid is lower than the warning dilution level, the delivery pump stops delivering the degumming water washing liquid in time. By controlling the liquid level in the degumming liquid recovery tank, it is ensured that the liquid level of the degumming liquid recovery tank is kept below the warning dilution level, thereby preventing the degumming water washing liquid from overflowing the degumming liquid recovery tank, and avoiding pollution and waste caused by the overflow of the degumming water washing liquid.

[0067] In one embodiment, the potassium permanganate degumming liquid includes potassium permanganate and NaOH, wherein the potassium permanganate concentration is 60g / L-80g / L, and the NaOH concentration is 35g / L-45g / L of NaOH. In this embodiment, due to the strong oxidizing property of potassium permanganate, potassium permanganate reacts chemically with the resin under high temperature and strong alkaline conditions, thereby decomposing and degumming the glue residue of the circuit board. The concentration of NaOH is 35g / L-45g / L, so that the potassium permanganate degumming liquid maintains a strong alkaline environment. The concentration of potassium permanganate is 60-80g / L, so that potassium permanganate has a better degumming effect on the glue residue on the circuit board, and the degumming amount of the potassium permanganate degumming liquid is relatively high. Mn 6+ The concentration of Mn affects the life of potassium permanganate degumming solution and the amount of degumming residue, so it is necessary to control the 6+ Less than 25g / L, by electrolyzing the regeneration device in the potassium permanganate degumming solution, Mn 6+ Regeneration to form high-priced Mn 7+ , thereby reducing the Mn 6+ The concentration of potassium permanganate affects the service life of potassium permanganate degumming liquid. Potassium permanganate is continuously regenerated through the regeneration device, so that the potassium permanganate degumming liquid can be used for degumming for a long time. The replacement cycle of the potassium permanganate degumming liquid in the degumming tank is half a year.

[0068] In one embodiment, the temperature of the potassium permanganate degumming solution in the degumming tank is 70° C.-85° C. In this embodiment, potassium permanganate and sodium hydroxide in the potassium permanganate degumming solution react with the glue residue of the circuit board. When the temperature of the potassium permanganate degumming solution is 70°C and the temperature is relatively low, the circuit board needs to be immersed in the potassium permanganate degumming solution for too long. When the immersion time is too long, potassium permanganate will damage the copper layer or substrate of the circuit board itself, resulting in a decrease in the electrical performance of the circuit board; when the temperature of potassium permanganate is greater than 85°C, the reaction speed of potassium permanganate is faster, and potassium permanganate is more likely to produce thermal decomposition, which increases the consumption of potassium permanganate, thereby reducing the service life of the potassium permanganate degumming solution; when the temperature of the potassium permanganate degumming solution in the degumming tank is 70°C-85°C, potassium permanganate reacts quickly with the glue residue of the circuit board, and the immersion time of the circuit board is shorter, thereby reducing the damage of potassium permanganate to the copper layer of the circuit board, and the consumption of potassium permanganate is less, thereby improving the quality of the circuit board and saving production costs.

[0069] In one embodiment, before placing the pre-neutralized circuit board in a neutralization tank and adding a neutralizer solution for neutralization, placing the circuit board after debonding in a pre-neutralization tank and adding a pre-neutralizer solution for pre-neutralization, the following steps are also included:

[0070] The circuit board after the pre-neutralization is washed with water. In this embodiment, the circuit board after the pre-neutralization has residual pre-neutralizer solution, potassium permanganate and other impurities. The residual potassium permanganate can be further reduced by washing with water, and the introduction of other impurities into the neutralization tank can be reduced, so that the neutralization effect of the neutralizer solution in the neutralization tank on the circuit board is improved, and the service life of the neutralizer solution in the neutralization tank is extended.

[0071] In one embodiment, the pre-neutralizer solution includes H2SO4 and H2O2, the volume percentage concentration of H2SO4 is 1%-2%, and the volume percentage concentration of H2O2 is 1%-2%; and / or, the neutralizer solution includes reducing organic acid and H2SO4, the volume percentage concentration of reducing organic acid is 18%-25%, and the volume percentage concentration of H2SO4 is 4%-6%. In this embodiment, 1%-2% H2SO4 is added to the pre-neutralizer solution, so that H2O2 reacts with potassium permanganate under acidic conditions, and the concentration of 1%-2% H2O2 can quickly consume the potassium permanganate remaining on the circuit board, and the low concentration of H2O2 has less oxidation effect on the circuit board. The neutralizer solution is a reducing organic acid and H2SO4. When the volume percentage concentration of the reducing organic acid in the neutralizer solution is less than 18%, the reaction speed of the neutralizer solution to the potassium permanganate of the circuit board is slow, which may cause residual potassium permanganate on the circuit board. When the volume percentage concentration of the reducing organic acid is greater than 25%, the acidity of the neutralizer solution is strong and it is easy to react with the copper layer of the circuit board. Therefore, the volume percentage concentration of the reducing organic acid is controlled at 18%-25%, so that the neutralizer solution can effectively remove the residual potassium permanganate on the circuit board, and the service life of the neutralizer solution is longer. The replacement cycle of the neutralizer solution in the neutralization tank is half a month.

[0072] In one embodiment, after placing the circuit board in the neutralization tank and adding a neutralizer solution for neutralization, the neutralized circuit board is washed with water to obtain the circuit board, and the following steps are also included:

[0073] The pre-neutralization cylinder is replenished with liquid, and the neutralizer solution after the neutralization reaction is transported to the pre-neutralization tank to replace the pre-neutralizer solution. In this embodiment, the pre-neutralizer solution in the pre-neutralization cylinder includes hydrogen peroxide and a low-concentration sulfuric acid solution. The hydrogen peroxide and hydrogen peroxide react with potassium permanganate under acidic conditions, thereby removing the potassium permanganate remaining on the circuit board. When the hydrogen peroxide is consumed, the hydrogen peroxide pre-neutralizer solution needs to be replenished. The neutralizer solution includes reducing organic acid and H2SO4. When the volume percentage concentration of reducing organic acid after the reaction of the neutralizer solution is less than 18%, the low-concentration reducing organic acid and H2SO4 after the neutralization reaction can be added to the pre-neutralization tank, consuming the reducing organic acid and H2SO4 of the low-concentration neutralizer solution. The low-concentration neutralizer solution replaces the pre-neutralizer solution, and H2SO4 is added to maintain an acidic reaction environment, thereby reducing the processing cost of the neutralizer solution, reducing the amount of H2O2 used, and extending the time for changing the pre-neutralization tank, further reducing the production cost. Specifically, for a production line with a monthly output of 40,000 to 50,000 square meters, when the neutralizer solution needs to be replaced every half month, the neutralizer solution is pumped to the pre-neutralization tank to replace the pre-neutralizer solution, so that the replacement cycle of the pre-neutralizer solution is extended from one day to one week, greatly reducing the amount of H2O2 used.

[0074] In one of the embodiments, the temperature of the pre-neutralizer solution in the pre-neutralizer tank is 25° C.-32° C., and the reaction time of the circuit board in the pre-neutralizer solution is 1 min-3 min. In this embodiment, since the reaction rate of the pre-neutralizer solution of hydrogen peroxide and potassium permanganate is relatively fast, the reaction time of the circuit board in the pre-neutralizer solution is relatively short. The pre-neutralizer solution is a hydrogen peroxide solution. When the temperature is lower than 25°C, the reaction rate of the hydrogen peroxide solution and potassium permanganate is relatively slow, resulting in poor neutralization effect of the pre-neutralizer solution on potassium permanganate; when the temperature is higher than 32°C, the hydrogen peroxide solution is unstable and easily decomposed, thereby rendering the pre-neutralizer solution ineffective and the effect of removing potassium permanganate is relatively poor, resulting in a high content of potassium permanganate remaining in the circuit board, thereby increasing the amount of the neutralizer solution used and increasing the production cost. Therefore, when the temperature of the pre-neutralizer solution in the pre-neutralization tank is 25°C-32°C, the neutralization efficiency of the pre-neutralizer solution on the potassium permanganate of the circuit board is relatively high, and the temperature of the pre-neutralizer solution is kept constant, thereby extending the service life of the pre-neutralization tank.

[0075] Furthermore, the neutralization time of the circuit board in the pre-neutralization tank is 1 min-3 min. After the low concentration of the neutralizer solution after the neutralization reaction is transported to the pre-neutralization tank to replace the pre-neutralizer solution, since the neutralizer solution is mainly a reducing organic acid such as oxalic acid, when the concentration of the reducing organic acid in the neutralizer solution is low, the reaction rate of the reducing organic acid with potassium permanganate is slow. Therefore, it is necessary to increase the reaction rate of the neutralizer solution with potassium permanganate. After the neutralizer solution after the neutralization reaction is transported to the pre-neutralization tank to replace the pre-neutralizer solution, the following steps are also included:

[0076] Sample the H2O2 concentration of the pre-neutralizer solution in the pre-neutralization tank and the concentration of the reducing organic acid in the neutralizer solution in the neutralization tank;

[0077] Calculate the difference between the H2O2 concentration of the pre-neutralizer solution and the reducing organic acid concentration of the neutralizer solution to obtain a neutralization concentration difference;

[0078] Whether the neutralization concentration difference is less than or equal to the preset concentration difference;

[0079] When the neutralization concentration difference is less than or equal to the preset concentration difference, the neutralization time of the circuit board in the pre-neutralization tank is extended by 0.5 min-1 min, and the temperature in the pre-neutralization tank is increased by 5° C.-10° C.

[0080] In this embodiment, the reducing organic acid has increased heat resistance relative to H2O2, so after the temperature is increased, the neutralizer solution after the reaction is not easy to overheat and decompose, and the preset concentration difference is 10%-12%. When the neutralization concentration difference is less than the preset concentration difference, the reducing organic acid concentration of the neutralizer solution is low, and the temperature of the pre-neutralization tank increases, so that the reaction rate of the reducing organic acid and potassium permanganate in the pre-neutralization tank is increased, and the neutralization time of the pre-neutralization tank is extended, ensuring that the potassium permanganate and the reducing organic acid of the circuit board react fully, thereby effectively removing the potassium permanganate remaining in the holes and on the board surface of the circuit board.

[0081] In one embodiment, the temperature of the neutralizer solution in the neutralization tank is 38°C-42°C, and the reaction time of the circuit board in the neutralizer solution is 3min-5min. In this embodiment, the organic acid in the neutralizer solution reacts with potassium permanganate under acidic conditions. When the temperature is less than 38°C, the reaction rate of the organic acid and potassium permanganate is slow, resulting in a longer time required for the organic acid to remove potassium permanganate; when the temperature is greater than 42°C, the organic acid is easily decomposed, thereby rendering the organic acid ineffective and reducing the use time of the neutralizer solution; when the temperature of the neutralizer solution in the neutralization tank is 38°C-42°C, the organic acid in the neutralizer solution can react with potassium permanganate faster, and the organic acid is more stable, thereby ensuring that the neutralizer solution effectively removes the potassium permanganate remaining on the circuit board and prolongs the service life of the neutralizer solution.

[0082] In one of the embodiments, the temperature of the leavening agent solution in the leavening tank is 70°C-80°C. In this embodiment, the leavening agent solution is sodium hydroxide and alcohol ether leavening agents, which are relatively gentle to the penetration of the resin. By heating the temperature to less than 70°C, the leavening agent solution has a slow leavening speed on the glue residue of the circuit board, and the circuit board needs to be soaked for a long time; when the temperature of the leavening agent solution is greater than 80°C, the alcohol ether leavening agent is less stable and decomposes or volatilizes, thereby affecting the leavening effect of the leavening agent and reducing the service life of the leavening agent solution; the temperature of the leavening agent solution is 70°C-80°C, so that the leavening agent solution maintains good infiltration of the circuit board, thereby achieving a better leavening effect of the circuit board and allowing the leavening agent solution to be used for a longer time.

[0083] Furthermore, in one embodiment, the leavening agent solution includes a leavening agent and NaOH, the volume ratio concentration of the leavening agent is 20%-40%, and the equivalent concentration of the NaOH is 0.6N-1.0N. In this embodiment, the equivalent concentration of NaOH in the leavening agent solution is 0.6N-1.0N, so that the leavening agent solution maintains an alkaline environment, and the leavening agent has a volume percentage concentration of 20%-40% under alkaline conditions to leaven and soften the glue residue of the circuit board, so that the leavening agent maintains the leavening effect on the glue residue of the circuit board, and the replacement cycle of the leavening agent solution is one month.

[0084] In one embodiment, after washing the puffed circuit board, placing the washed circuit board in a degumming tank, adding potassium permanganate degumming solution and heating it before degumming, the following steps are also included:

[0085] The expanded circuit board is moved into an expansion recovery tank for water washing, wherein the expansion recovery tank stores a water washing liquid of an expansion agent;

[0086] The leavening agent water washing liquid in the leavening recovery tank is transported to the leavening tank to replenish the leavening agent solution. In this embodiment, after the expanded circuit board is washed with water, the leavening water washing liquid can be collected by the leavening recovery tank. The leavening water washing liquid contains water and leavening agent. When the leavening tank is heated, the water will evaporate continuously. By replenishing the leavening water washing liquid to the leavening tank, the water lost in the leavening tank can be replenished, and the leavening water washing liquid can be consumed at the same time, so that the leavening agent remaining in the leavening water washing liquid is fully utilized, and the discharge of the leavening water washing liquid is avoided, and the cost of processing the leavening water washing liquid is reduced.

[0087] Furthermore, in one embodiment, when the bulking recovery tank washes the circuit board with water, the bulking water washing liquid collected by the bulking recovery tank includes leavening agent, resin fragments, glue and other residues. Directly conveying the bulking water washing liquid to the bulking tank will reintroduce resin fragments, glue and other residues. Therefore, before conveying the leavening agent water washing liquid of the bulking recovery tank to the bulking tank, the following steps are also included:

[0088] The leavening agent water wash liquid is extracted from the leavening recovery tank, and the leavening agent water wash liquid is filtered to remove resin fragments, glue and other residues to obtain a filtered leavening agent water wash liquid;

[0089] The filtered leavening agent water washing liquid is heated, wherein the temperature of the filtered leavening agent water washing liquid is 70° C.-75° C., and the heated leavening agent water washing liquid is transported to the leavening tank.

[0090] In this embodiment, by filtering the leavening agent water washing liquid, the impurities in the leavening agent water washing liquid are reduced, thereby avoiding the leavening agent water washing liquid to reintroduce impurities into the leavening recovery tank, and the effective leavening agent in the leavening agent water washing liquid is utilized, thereby reducing the treatment and discharge of the leavening agent water washing liquid, thereby reducing the treatment cost; by heating the filtered leavening agent water washing liquid, the temperature difference between the leavening agent water washing liquid and the leavening agent solution in the leavening tank is small, thereby avoiding the influence of the leavening agent water washing liquid transported to the leavening recovery tank on the temperature of the leavening agent solution, thereby allowing the leavening agent solution to maintain a good leavening effect on the circuit board.

[0091] Compared with the prior art, the present invention has at least the following advantages:

[0092] The above-mentioned degumming method for recycling and reusing materials of circuit boards moves the degumming circuit boards into a degumming liquid recovery tank for water washing, and the degumming water washing liquid collected by the degumming liquid recovery tank is transported to the degumming tank, thereby avoiding direct discharge and treatment of the degumming water washing liquid. By consuming the degumming water washing liquid, the potassium permanganate of the degumming water washing liquid is recycled and reused, and the production cost of the degumming method is reduced;

[0093] The potassium permanganate of the degumming solution in the degumming solution recovery tank is diluted with clean water, so that the degumming solution is kept at a low concentration to clean the circuit board, reducing the residual potassium permanganate on the circuit board, thereby reducing the use of subsequent pre-neutralizer solution, thereby extending the service life of the pre-neutralizer solution and reducing production costs.

[0094] By replenishing the pre-neutralization cylinder with a neutralizer solution, and conveying the neutralizer solution after the neutralization reaction to the pre-neutralization tank to replace the pre-neutralizer solution, the neutralizer solution can be further utilized, and the consumption of the neutralizer solution can reduce the discharge treatment of the neutralizer solution, thereby reducing the production cost; by replacing the pre-neutralizer solution with a high-concentration neutralizer solution for pre-neutralization, the service life of the pre-neutralizer solution in the pre-neutralization cylinder is extended, thereby saving production costs.

[0095] The above-mentioned embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the disclosed patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the disclosed patent shall be subject to the attached claims.

Claims

1. A method for removing glue from recycled materials of circuit boards, characterized in that: The following steps are involved: Place the circuit board in the expansion tank, add the expansion agent solution and heat it to soften and expand it; Washing the softened and expanded circuit board with water; Put the washed circuit board into a degumming tank, add potassium permanganate degumming solution and heat to remove the glue; The debonded circuit board is moved into a debonding liquid recovery tank for water washing, wherein the debonding liquid recovery tank stores debonding water washing liquid; The degumming liquid in the degumming liquid recovery tank is transported to the degumming tank to replenish the potassium permanganate degumming liquid in the degumming tank, and clean water is added to the degumming liquid recovery tank to dilute the degumming liquid in the degumming liquid recovery tank; Putting the circuit board after debonding into a pre-neutralization tank, adding a pre-neutralizer solution for pre-neutralization; Putting the pre-neutralized circuit board into a neutralization tank, and adding a neutralizer solution for neutralization; The neutralized circuit board is washed with water to obtain a circuit board.

2. The method for removing glue from recycled circuit board materials according to claim 1, characterized in that: The concentration of potassium permanganate after dilution of the degumming water washing solution in the degumming solution recovery tank is less than 5g / L.

3. The method for removing glue from recycled circuit board materials according to claim 1, characterized in that: The temperature of the potassium permanganate degumming solution in the degumming tank is 70° C.-85° C., and the degumming time of the circuit board is 10 min-15 min.

4. The method for removing glue from recycled circuit board materials according to claim 1, characterized in that: Before placing the pre-neutralized circuit board into a neutralization tank and adding a neutralizer solution for neutralization, placing the circuit board after debonding into a pre-neutralization tank and adding a pre-neutralizer solution for pre-neutralization, the following steps are also included: The pre-neutralized circuit board is washed with water.

5. The method for removing glue from recycled circuit board materials according to claim 1, characterized in that: The pre-neutralizer solution includes H2SO4 and H2O2, wherein the volume percentage concentration of H2SO4 is 1%-2%, and the volume percentage concentration of H2O2 is 1%-2%; and / or, The neutralizer solution includes reducing organic acid and H2SO4, the volume percentage concentration of the reducing organic acid is 18%-25%, and the volume percentage concentration of the H2SO4 is 4%-6%.

6. The method for removing glue from recycled circuit board materials according to claim 5, characterized in that: After placing the circuit board in the neutralization tank and adding a neutralizer solution for neutralization, the neutralized circuit board is washed with water to obtain the circuit board, and the following steps are also included: The low-concentration neutralizer solution after the neutralization reaction is transported to the pre-neutralization tank to replace the pre-neutralizer solution.

7. The method for removing glue from recycled circuit board materials according to claim 1, characterized in that: The temperature of the pre-neutralizer solution in the pre-neutralizer tank is 25° C.-32° C., and the reaction time of the circuit board in the pre-neutralizer solution is 1 min-3 min.

8. The method for removing glue from recycled circuit board materials according to claim 1, characterized in that: The temperature of the neutralizer solution in the neutralization tank is 38° C.-42° C., and the reaction time of the circuit board in the neutralizer solution is 3 min-5 min.

9. The method for removing glue from recycled circuit board materials according to claim 1, characterized in that: The temperature of the leavening agent solution in the leavening tank is 70°C-80°C.

10. The method for removing glue from recycled circuit board materials according to claim 1, characterized in that: After washing the expanded circuit board, the washed circuit board is placed in a degumming tank, and before adding potassium permanganate degumming solution and heating for degumming, the following steps are also included: The expanded circuit board is moved into an expansion recovery tank for water washing, wherein the expansion recovery tank stores a water washing liquid of an expansion agent; The leavening agent water washing liquid of the leavening recovery tank is transported to the leavening tank to replenish the leavening agent solution.

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