Cyclic regeneration process and equipment for PCB (Printed Circuit Board) acidic etching waste liquid

Abstract

The invention relates to the technical field of etching liquid treatment, in particular to a PCB acid etching waste liquid cyclic regeneration process and equipment, the PCB acid etching waste liquid cyclic regeneration process comprises the working procedures of etching, electrolysis, filtration, mixing, chlorine gas absorption, air floatation and regeneration, and a filter membrane in the filtration working procedure comprises a PES membrane, a PS membrane or an SPS membrane. Chlorine absorbed in the chlorine absorption process is conveyed on an electrolysis line in a jet mode, and gas blown in the air flotation process is air, oxygen or nitrogen; through the procedures, a light agent and impurities are effectively filtered out, chlorine gas micro bubbles are completely discharged while chlorine gas fully reacts, the problems of poor etching efficiency and poor etching quality caused by a diaphragm electrolysis process in the prior art are solved, and meanwhile, the risk of chlorine gas leakage and energy consumption are reduced; the relevance between an etching line and an electrolytic line is further reduced; and the recycling efficiency of chlorine and regenerated liquid reaches 70-90%.

Description

Technical Field

[0001] The invention relates to the technical field of etching liquid treatment, and in particular to a recycling process and equipment for PCB acid etching waste liquid. Background Art

[0002] Etching is an essential step in PCB manufacturing. Acid etching is a common etching method, which produces a large amount of high-acid, high-copper etching waste liquid, causing environmental pollution. Regeneration treatment is needed to effectively reduce the emission of harmful substances, mitigate negative impacts on the environment, and achieve the recycling of etching waste liquid to save resources.

[0003] At present, the common regeneration processes on the market mainly include diaphragm or ion membrane electrolysis. Diaphragm electrolysis is the most commonly used method. For example, patent CN109972139A discloses a regeneration and circulation method for an acidic etching solution. The etching waste liquid tank collects the waste liquid generated by the acid etching line (DES) and transports it to the electrolytic cell. The electrolytic cell electrolyzes the waste liquid, converts the copper ions in the waste liquid into electrolytic copper plates, and oxidizes the chloride ions in the waste liquid into chlorine gas. The acid mist absorption cylinder collects the waste liquid in the electrolytic cell and reacts with the chlorine gas generated in the electrolytic cell to obtain a regenerated etching solution.

[0004] Patent CN117026303A discloses a method for recovering copper from acidic etching waste liquid and co-regenerating etching liquid. The cleaning water is purified and concentrated, and the cleaning water concentrate is mixed with the acidic etching waste liquid. Then, sodium alginate and dodecyltrimethylammonium bromide are added to perform diaphragm electrolysis to recover cathode copper. The low-copper, high-acid electrolytic clear liquid after copper recovery and the chlorine generated at the anode are both reused in the acid etching production line. The chlorine generated at the anode is mixed with the acidic etching liquid to supplement the insufficient oxidant in the online recycling regeneration process of the acidic etching liquid; the low-copper, high-acid electrolytic clear liquid is reused in the acid etching production line to supplement the insufficient hydrochloric acid, effectively reducing etching costs and maximizing the recovery of copper resources.

[0005] Patent CN114481221A discloses a copper extraction method using a recyclable acidic etching solution, in which chlorine is transported to a chlorine dissolving and absorbing tank through an ejector, the regenerated etching solution is transported to the chlorine dissolving and absorbing tank to react with chlorine, and the reacted etching solution is then transported to an acid etching line. The processed etching solution is returned to the chlorine dissolving and absorbing tank, the etching solution is reprocessed with chlorine, and the etching solution is transported to an etching waste liquid tank.

[0006] In the existing diaphragm electrolysis method, the chlorine gas generated at the anode during the electrolysis process is returned to the etching line through a jet to act as an oxidant, which can reduce the amount of oxidant used. The residual liquid after electrolysis mainly contains hydrochloric acid and etching salt, which can be returned to the etching line to act as hydrochloric acid, which can reduce the amount of hydrochloric acid used and reduce the material cost of the etching line.

[0007] However, due to problems such as insufficient chlorine reaction and residual photopolymer in the regeneration liquid, the existing process leads to abnormal phenomena such as rate drop and deterioration of etching factor in the etching line after reuse, which reduces the reuse rate of chlorine and regeneration liquid, seriously affecting the efficiency and production capacity of the etching line. At the same time, the chlorine generated during the electrolysis process needs to be transported to the etching line over a long distance, which has the risk of leakage and poses great harm to the environment. Summary of the Invention

[0008] In order to solve the problem of poor etching factor and etching efficiency in the process of etching solution regeneration and reuse using the diaphragm electrolysis process in the existing technology, the present invention provides a PCB acid etching waste liquid recycling and regeneration process and equipment, which improves the etching efficiency and etching quality while increasing the reuse rate of chlorine and regeneration liquid.

[0009] A PCB acid etching waste liquid recycling and regeneration process, comprising etching → electrolysis → chlorine absorption → regeneration steps, and also comprising a filtration step and a flotation step, wherein the filtration step is located between the electrolysis step and the chlorine absorption step, and the flotation step is located between the chlorine absorption step and the regeneration step;

[0010] A mixing process of the filtrate and the etching waste liquid is also provided between the filtration process and the chlorine absorption process;

[0011] The chlorine absorbed in the chlorine absorption process is transported on the electrolysis line in a jet manner, and the chlorine discharged in the flotation process enters the waste gas treatment system for treatment.

[0012] Preferably, the recycling regeneration process also includes a flotation process and a filtration process connected in sequence, and the flotation process and the filtration process are located between the chlorine absorption process and the regeneration process; and a mixing process of cathode low-copper liquid and etching waste liquid is also provided between the electrolysis process and the chlorine absorption process.

[0013] Furthermore, the filter membrane used in the filter assembly in the filtration process includes a PES membrane, a PS membrane or an SPS membrane.

[0014] Furthermore, the mixed solution output from the mixing step has a copper ion concentration of 70-120 g / L, an acidity of 1.5-3.0 mol / L, a chloride ion concentration of 200-330 g / L, and a specific gravity of 1.1-1.3.

[0015] Furthermore, in the chlorine absorption process, the delivery of chlorine is controlled by monitoring the ORP value, and when the ORP is ≥450mV, the delivery of chlorine is stopped.

[0016] Furthermore, the gas blown in during the flotation process is air, oxygen or nitrogen.

[0017] Furthermore, the additives in the regeneration process include etching bank protection agents and etching accelerators.

[0018] Furthermore, the temperature of the regenerated sub-liquid in the regeneration process is 40-60°C.

[0019] Furthermore, the material flow in the recycling process is as follows:

[0020] The acidic etching liquid is subjected to the etching process to obtain etching waste liquid, and the obtained etching waste liquid flows into the electrolysis process to obtain chlorine and cathode low-copper liquid. The obtained cathode low-copper liquid is treated in the filtration process and then mixed with the etching waste liquid in the mixing process to obtain a mixed liquid. The obtained mixed liquid then enters the chlorine absorption process to obtain an absorption liquid, and then the chlorine is discharged through the flotation process to obtain a regenerated liquid. The discharged chlorine enters the waste gas treatment system for treatment, and the obtained regenerated liquid enters the regeneration process to obtain a regenerated sub-liquid and is then reused in the etching production line.

[0021] Based on the above process, the present invention also provides a PCB acid etching waste liquid recycling and regeneration equipment, including an etching machine, a waste liquid barrel, an electrolytic cell, a chlorine absorption cylinder, and a regeneration sub-liquid barrel connected in sequence, and also including a cathode low-copper liquid barrel, a filter component, a mixing barrel and an air flotation cylinder. The cathode low-copper liquid barrel, the filter component, and the mixing barrel are connected in sequence and arranged between the electrolytic cell and the chlorine absorption cylinder; the air flotation cylinder is arranged between the chlorine absorption cylinder and the regeneration sub-liquid barrel; wherein the air flotation cylinder and the chlorine absorption cylinder are connected through a fourth pump.

[0022] Furthermore, the filtration component includes a membrane filter and a filtrate barrel, a first pump is provided between the membrane filter and the cathode low-copper liquid barrel, and a second pump is provided between the filtrate barrel and the mixing barrel.

[0023] Furthermore, a specific gravity detector is provided in the mixing barrel, and the feed end of the mixing barrel is connected to the discharge end of the waste liquid barrel and the overflow port of the filtrate barrel respectively.

[0024] Furthermore, an ORP detector is provided in the chlorine absorption cylinder, the chlorine absorption cylinder is arranged next to the electrolytic cell, the chlorine absorption cylinder and the electrolytic cell are connected through an ejector, and a third pump is provided between the chlorine absorption cylinder and the mixing barrel.

[0025] Furthermore, an air-blowing device, an air return port and a liquid level sensor are provided in the air flotation cylinder. The air return port is connected to the waste gas treatment device. The air flotation cylinder and the chlorine absorption cylinder are connected via a fourth pump.

[0026] Furthermore, the regeneration sub-liquid barrel is provided with a feeding port and a heating device, and the feeding port is communicated with the feeding port of the additive.

[0027] Preferably, the PCB acid etching waste liquid recycling and regeneration equipment further includes a PLC controller, and the PLC controller is independently connected to the etcher, the mixing barrel, the chlorine absorption cylinder, the air flotation cylinder, and the regeneration sub-liquid barrel.

[0028] The advantages of the present invention are:

[0029] 1. The present invention processes the cathode low-copper liquid obtained by electrolysis through a filtering process, a mixing process, a chlorine absorption process, a flotation process, and a regeneration process, and reuses it in the etching line. In this process, the light agent and impurities are filtered out, the chlorine is fully reacted, and the tiny chlorine bubbles are completely discharged. This effectively solves the problems of poor etching efficiency and etching quality caused by the diaphragm electrolysis process in the prior art, and the reuse efficiency of chlorine and regeneration liquid reaches 70-90%, thereby reducing production costs.

[0030] 2. The present invention sets the chlorine absorption cylinder next to the electrolytic cell. Compared with the prior art where it is set on the etching line, the present invention sets it on the electrolysis line, which can process chlorine nearby, reducing the risk of chlorine leakage and the energy consumption of transporting and treating chlorine. It further reduces the correlation between the etching line and the electrolysis line, and the two can operate independently without affecting each other.

[0031] 3. The temperature of the recycled regeneration liquid of the present invention is 40-60°C, which is close to the working temperature of the etching line. Compared with the prior art, the temperature fluctuation caused by the one-time addition of regeneration liquid is reduced during the recycling process, the impact on the etching process is reduced, and the etching efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a process flow chart of recycling and regenerating the PCB acid etching waste liquid of the present invention;

[0033] Figure 2 This is a schematic diagram of the connection of the PCB acid etching waste liquid recycling and regeneration equipment of the present invention;

[0034] Figure 3 is an etching factor diagram of the regenerated liquid reused in the process of Example 1 of the present invention during the etching process;

[0035] Figure 4 is an etching factor diagram of the regenerated liquid reused in the process of Example 2 of the present invention during the etching process;

[0036] Figure 5 is an etching factor diagram of the regenerated liquid reused in the process of Example 3 of the present invention during the etching process;

[0037] Figure 6 is an etching factor diagram of the regenerated liquid reused in the process of Example 4 of the present invention during the etching process;

[0038] Figure 7This is an etching factor diagram of the regenerated liquid recycled in the process of comparative example 1 of the present invention during the etching process;

[0039] Figure 8 This is an etching factor diagram of an etching working fluid that does not contain a regenerated liquid and has not been recycled during the etching process. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] It should be noted that the various installation methods and technical terms mentioned in the present invention are technical terms that have long been clearly known in the relevant technical field and therefore will not be further explained. In addition, the same reference numerals are used for the same components, but this does not affect nor constitute an accurate understanding of the technical solution by those skilled in the art.

[0042] Example 1

[0043] This embodiment 1 provides a PCB acid etching waste liquid recycling process, such as Figure 1 As shown, the process includes etching → electrolysis → filtration → mixing → chlorine absorption → flotation → regeneration. The specific process is as follows:

[0044] (1) Etching process: Acidic etching solution is used for etching in an etching machine, and the generated etching waste liquid flows through the overflow pipe of the etching machine to a waste liquid barrel for storage;

[0045] (2) Electrolysis process: a portion of the etching waste liquid in the waste liquid barrel of step (1) is sent to the electrolytic cell for electrolysis treatment, the chlorine gas obtained in the anode chamber is controlled by the ejector on the electrolysis line and sent to the chlorine absorption cylinder, and the cathode low copper liquid obtained in the cathode chamber flows through the overflow pipe to the cathode low copper liquid barrel for storage;

[0046] (3) Filtration process: The cathode low-copper liquid collected in the cathode low-copper liquid barrel in step (2) is sent to the membrane filter of the filtration assembly through a first pump, and enters the liquid inlet of the membrane filter (the filter membrane in the membrane filter of this embodiment is a PES membrane). The components such as the light agent in the cathode low-copper liquid are filtered out by the PES membrane, and the resulting pure filtrate is collected in the filtrate barrel;

[0047] (4) Mixing process: the pure filtrate collected in step (3) is sent to a mixing barrel by a second pump, and mixed with another portion of the etching waste liquid from the waste liquid barrel in the mixing barrel, and the specific gravity of the mixed liquid is monitored by a specific gravity detector in the mixed liquid barrel, and the ratio of the etching waste liquid and the pure cathode liquid is adjusted to obtain a copper ion concentration of 70 g / L, an acidity of 3.0 mol / L, a chloride ion concentration of 200 g / L, and a specific gravity of 1.1 in the obtained mixed liquid;

[0048] (5) Chlorine absorption process: The mixed solution obtained in step (4) is pumped into the chlorine absorption cylinder (containing a large amount of Cu + ), reacting with the chlorine gas delivered from the anode chamber, and monitoring the ORP value of the mixed liquid in the cylinder by the ORP detector in the chlorine absorption cylinder when it is greater than 450mV, stopping the delivery of chlorine gas to obtain the absorption liquid;

[0049] (6) Flotation process: The absorption liquid obtained in step (5) is pumped into the flotation cylinder by a fourth pump, the liquid level of the absorption liquid is monitored by a liquid level sensor in the flotation cylinder, and air is blown into the flotation cylinder by an air blowing device to discharge all the chlorine gas bubbles dissolved in the absorption liquid to obtain a regenerated liquid. The discharged chlorine gas is sent to the waste gas treatment device through the return air port for treatment and is discharged after being tested to meet the standards;

[0050] (7) Regeneration process: The regenerated liquid obtained in step (6) is sent to the regenerated sub-liquid barrel, and the etching revetment agent and etching accelerator are appropriately supplemented according to the needs of the etching production line (the etching revetment agent in this embodiment is purchased from Huizhou Ruixiangfeng Technology Co., Ltd., and the etching accelerator is copper sulfate) to obtain the regenerated sub-liquid, and the temperature of the regenerated sub-liquid is controlled at 40°C by the heating device in the regenerated sub-liquid barrel. According to the ORP requirements of the etching production line, the amount of regenerated sub-liquid added back to the production line is controlled for recycling.

[0051] The connection method of the regeneration device used in this embodiment is as follows Figure 2 shown.

[0052] The etching effect of the regenerated sub-liquid obtained by the regeneration process of this embodiment is shown in Table 1. The etching factor corresponding to the etching quality is shown in Table 1. Figure 3 shown.

[0053] Example 2

[0054] The process and equipment used in the recycling and regeneration of PCB acid etching waste liquid in Example 2 are the same as those in Example 1. The difference lies in that the parameters involved in the process are different:

[0055] In the filtration step of this embodiment, the membrane used in the membrane filter is a PS membrane. The specific gravity of the mixed solution is monitored by a specific gravity detector in the mixed solution bucket, and the ratio of the etching waste liquid and the pure cathode liquid is adjusted to obtain a mixed solution with a copper ion concentration of 120 g / L, an acidity of 1.5 mol / L, a chloride ion concentration of 330 g / L, and a specific gravity of 1.3.

[0056] In this embodiment, nitrogen is blown into the cylinder through a blower to expel all the tiny bubbles of chlorine dissolved in the absorption liquid to obtain a regenerated liquid;

[0057] The temperature of the regenerated sub-liquid in the reuse filtration step of this embodiment is controlled at 60°C.

[0058] The etching effect of the regenerated sub-liquid obtained by the regeneration process of this embodiment is shown in Table 1. The etching factor corresponding to the etching quality is shown in Table 1. Figure 4 shown.

[0059] Example 3

[0060] Compared with Example 1, this Example 3 is different in that this Example does not have a filtration process and corresponding filtration component equipment. The cathode low-copper liquid obtained by electrolytic treatment of the etching waste liquid is directly mixed with the waste liquid in the waste liquid barrel and enters the absorption process to absorb chlorine, and then the subsequent flotation process and reuse process are carried out.

[0061] The etching effect of the regenerated sub-liquid obtained by the regeneration process of this embodiment is shown in Table 1. The etching factor corresponding to the etching quality is shown in Table 1. Figure 5 shown.

[0062] Example 4

[0063] Compared with Example 1, Example 4 is different in that this example does not have a flotation process and corresponding flotation cylinder equipment, and the regenerated liquid obtained by the chlorine absorption process directly enters the reuse process for treatment.

[0064] The etching effect of the regenerated sub-liquid obtained by the regeneration process of this embodiment is shown in Table 1. The etching factor corresponding to the etching quality is shown in Table 1. Figure 6 shown.

[0065] Comparative Example 1

[0066] The recycling process of PCB acid etching waste liquid used in this comparative example 1 is the diaphragm electrolysis process in the prior art, which does not involve the flotation process and the filtration process. The etching effect of the obtained regenerated sub-liquid is shown in Table 1. The etching factor corresponding to the etching quality is shown in Table 1. Figure 7 shown.

[0067] Table 1 shows the recycling effects of the embodiments and comparative examples.

[0068]

[0069] From Table 1 and Figure 3-8 The results show that the process treatment in which the filtration step and the flotation step are simultaneously performed in Examples 1 and 2 of the present invention has the highest etching efficiency and recycling efficiency of the regenerated liquid used in the etching line, and the best etching quality, which is not much different from the etching working liquid without recycling treatment ( Figure 8 (Figure 2 is the etching factor diagram of the etching working liquid without reuse treatment). The etching efficiency and etching quality of Example 3 lacking the filtering process and Example 4 lacking the flotation process will decrease during reuse, which is quite different from the etching working liquid without reuse treatment, affecting the reuse efficiency. The regenerated liquid obtained by the comparative example 1 without the filtering process and the flotation process is the worst, with both the etching rate and the etching quality not meeting the standards, and the reuse efficiency is as low as 40%. Therefore, the filtering process and the flotation process of the present invention need to exist at the same time to achieve the best effect. Both are indispensable. Alternatively, the flotation process can be carried out first to eliminate chlorine and then the filtering process can be carried out to filter out impurities such as light-removing agents. However, the amount of liquid processed in this way will be large, which will reduce production efficiency. Therefore, the preferred solution is to carry out the filtering process first to filter out light-removing agents and impurities and then the flotation process, which can improve work efficiency and reduce production costs.

[0070] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention may be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the foregoing description. It is intended that all variations that fall within the meaning and range of equivalents of the claims be embraced within the present invention. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any minor modifications, equivalent replacements, and improvements made to the above embodiments based on the technical essence of the present invention shall be included in the scope of protection of the technical solution of the present invention.

Claims

1. A PCB acid etching waste liquid recycling process, comprising etching → electrolysis → chlorine absorption → regeneration process, characterized in that: It also includes a filtration process and a flotation process, wherein the filtration process is located between the electrolysis process and the chlorine absorption process, and the flotation process is located between the chlorine absorption process and the regeneration process; A mixing process of the filtrate and the etching waste liquid is also provided between the filtering process and the chlorine gas absorption process; The chlorine absorbed in the chlorine absorption process is transported on the electrolysis line in the form of a jet, and the chlorine discharged in the flotation process enters a waste gas treatment system for treatment.

2. A PCB acid etching waste liquid recycling process according to claim 1, characterized in that: It also includes a flotation process and a filtration process connected in sequence, wherein the flotation process and the filtration process are located between the chlorine absorption process and the regeneration process; and a mixing process of cathode low-copper liquid and etching waste liquid is also provided between the electrolysis process and the chlorine absorption process; The chlorine absorbed in the chlorine absorption process is transported on the electrolysis line in the form of a jet, and the chlorine discharged in the flotation process enters a waste gas treatment system for treatment.

3. A PCB acid etching waste liquid recycling process according to claim 1 or 2, characterized in that: The filter membrane used in the filter assembly in the filtering process includes a PES membrane, a PS membrane or a SPS membrane.

4. A PCB acid etching waste liquid recycling process according to claim 3, characterized in that: The mixed solution outputted from the mixing step has a copper ion concentration of 70-120 g / L, an acidity of 1.5-3.0 mol / L, a chloride ion concentration of 200-330 g / L, and a specific gravity of 1.1-1.

3.

5. A PCB acid etching waste liquid recycling process according to claim 1 or 2, characterized in that: In the chlorine absorption process, the delivery of chlorine is controlled by monitoring the ORP value, and when ORP≥450mV, the delivery of chlorine is stopped.

6. A PCB acid etching waste liquid recycling process according to claim 1 or 2, characterized in that: The gas blown in during the flotation process is air, oxygen or nitrogen.

7. A PCB acid etching waste liquid recycling process according to claim 1 or 2, characterized in that: The temperature of the regenerated sub-liquid in the regeneration process is 40-60°C.

8. A PCB acid etching waste liquid recycling and regeneration equipment based on any one of claims 1 to 7, comprising an etching machine, a waste liquid barrel, an electrolytic cell, a chlorine gas absorption cylinder, and a regeneration sub-liquid barrel connected in sequence, characterized in that: It also includes a cathode low-copper liquid barrel, a filter assembly, a mixing barrel and an air flotation cylinder, wherein the cathode low-copper liquid barrel, the filter assembly and the mixing barrel are connected in sequence and arranged between the electrolytic cell and the chlorine absorption cylinder; the air flotation cylinder is arranged between the chlorine absorption cylinder and the regeneration sub-liquid barrel; Wherein, the air flotation cylinder is connected to the chlorine absorption cylinder via a fourth pump.

9. The PCB acid etching waste liquid recycling and regeneration equipment according to claim 8, characterized in that: The filtering assembly comprises a membrane filter and a filtrate barrel, a first pump is provided between the membrane filter and the cathode low copper liquid barrel, and a second pump is provided between the filtrate barrel and the mixing barrel; The air flotation cylinder is provided with an air-inflating device, an air return port and a liquid level sensor, and the air return port is connected to the exhaust gas treatment device; The regeneration sub-liquid barrel is provided with a feeding port and a heating device, and the feeding port is communicated with a feeding port for additives.

10. The process equipment for recycling PCB acid etching waste liquid according to claim 9, characterized in that: A specific gravity detector is provided in the mixing barrel, and a feed end of the mixing barrel is connected to a discharge end of the waste liquid barrel and an overflow port of the filtrate barrel respectively; An ORP detector is arranged in the chlorine absorption cylinder, the chlorine absorption cylinder is arranged beside the electrolytic cell, the chlorine absorption cylinder and the electrolytic cell are connected through an ejector, and a third pump is arranged between the chlorine absorption cylinder and the mixing barrel.

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