Solventless copper extraction

Abstract

The systems and methods described herein provide for the removal of excess copper using ion exchange resins during processes such as PCB (printed circuit board) manufacturing using copper chloride etchant. Cu +2 For oxidizing solid copper, two Cu + ions are produced. During operation, the etchant is overloaded with copper ions, and an extraction system is implemented to control the concentration and remove excess copper. Traditional systems use liquid extraction, but these systems can be expensive and use hazardous solvents. Ion exchange resins are used as a solution for controlling concentration, adsorbing metal ions, and retaining them until desorption. The system and method further determine the effectiveness of the resins in removing copper based on performing adsorption and desorption at different flow rates. The results show that the resins effectively remove copper at various flow rates, removing an average of 10.06 g / l of Cu from the total value of three-bed etchant.

Description

Cross-reference to related applications

[0001] This PCT application claims priority to U.S. Provisional Application No. 63 / 616,120, filed December 29, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to a system and method for controlling the copper concentration in an etchant, and particularly to the use of an ion exchange resin to adsorb copper ions during acid etching. Furthermore, any copper ions adsorbed by the resin during the etching process can be recovered by desorption. Background Technology

[0003] Solvent extraction technology is known to be used for metal recovery and large-scale metal production. Solvents are particularly used to extract copper from solutions with varying pH values. This leaching of copper can vary based on the pH of the solution. When dissolved in water as ions, the metal can be highly hazardous to human and environmental health. The separation of specific metals is crucial for efficient metal production and environmental management. Liquid-liquid extraction is the most common and conventional method for the selective separation of metals, but it requires harmful and environmentally detrimental organic solvents. Other conventional systems for extracting excess copper ions may rely on direct plating methods, which can produce volatile gases such as chlorine.

[0004] Solvent extraction technology can be applied during the manufacturing of printed circuit boards (PCBs), where etching is required to remove unwanted or excess materials, such as copper, from the substrate, leaving only the copper needed to form the desired circuitry. A common type of etching is chemical etching, which relies on using a liquid reactant, such as copper chloride, to precisely etch features of the PCB. To control the copper concentration, an extraction system is implemented to remove excess copper. Acidic copper chloride etching systems have become common in PCB manufacturing. The copper chloride etchant used to remove copper in PCB manufacturing utilizes Cu... +2 (Copper ions carrying two positive charges) are used to oxidize the solid copper on the PCB substrate. This etching produces two Cu... + The etchant can become overloaded with these copper ions during the etching operation. However, these systems use potentially expensive liquid-liquid extraction, employ harmful solvents, and generate hazardous waste, including during organic solvent replacement.

[0005] For example, acidic copper chloride etching systems use divalent copper (Cu). 2+ The oxidation and dissolution of solid copper produce two monovalent copper molecules (Cu1) in the solution. +) ions, as shown in Formula 1.

[0006] Formula 1, Etching process:

[0007] Furthermore, divalent copper is regenerated by oxidizing monovalent copper, which allows etching to continue (Equation 2).

[0008] Formula 2, Regeneration of divalent copper:

[0009] While it is possible to electrodeposit copper from etchants, this process is extremely hazardous as it releases chlorine gas. Therefore, PCB manufacturers rely on liquid-liquid extraction (LLE) units for extraction. The process begins by mixing a copper-rich etchant with an immiscible organic solvent. The solvent extracts copper ions from the etchant, and the etchant / organic mixture is then settled, separating the two liquid phases. The regenerated etchant is returned to the etching machine while the copper-rich organic solvent moves to the next extraction unit. The copper-rich organic solvent is then mixed with an immiscible acid electrolyte, which extracts copper from the solvent, thus regenerating the solvent. The immiscible liquid is settled and separated, with the regenerated organic solvent recycled back to be mixed with the etchant again. The acid electrolyte then moves to an electrowinning cell, where copper is electroplated from the solution, regenerating the acid electrolyte. This process requires at least two LLE mixer or settler units, although multiple countercurrent extractors are typically needed to remove a sufficient amount of copper.

[0010] While etchant regeneration is common, liquid-liquid extraction (LLE) has several drawbacks. First, these systems use large quantities of hazardous and expensive organic solvents that must be frequently metered and eventually replaced. These solvents pose an environmental hazard and cannot be handled using conventional waste management systems found in PCB factories. This means manufacturers will have a hazardous waste stream when disposing of the solvents. Second, LLE systems require significant floor space and operate using hundreds of gallons of chemicals. Third, LLE systems are prone to accidents. Cross-contamination of liquids such as organic solvents in the etchant regeneration tank can cause system failures, potentially shutting down the etching pipeline for days.

[0011] Therefore, there is a need for improved methods to remove copper from a given volume of etchant without using expensive and harmful ingredients such as organic solvents. Summary of the Invention

[0012] The objects and advantages of the present invention will be set forth in and will become apparent from the following description. Further advantages of the invention will be realized and obtained by means of the methods and systems particularly pointed out in the description and claims herein and from the accompanying drawings.

[0013] This invention relates to a system and method for removing excess copper using ion exchange resins, wherein these resins adsorb metal ions and retain them until desorption is applied. Ion exchange is a separation method in which a solid-phase adsorbent captures desired ions from a fluid and replaces them with less desirable ions of the same charge. Ion exchange resins are frequently used to recover metals from process waste streams. Efficacy studies were conducted using small-scale columns, where adsorption and desorption were performed at different flow rates. Results showed that this ion exchange resin effectively removed copper at a variety of flow rates. The extraction process using ion exchange resins further demonstrates environmental friendliness, for example, by minimizing waste by only wasting copper plates. Copper excess is extracted from etchants such as copper chloride etchants. To control the concentration, an extraction system is implemented to remove excess copper. Ion exchange resins are used as a solution for controlling the concentration, adsorbing metal ions, and retaining them until desorption. The system and method are further based on adsorption and desorption performed at different flow rates to determine the resin's effectiveness in removing copper.

[0014] This system and method utilize ion exchange resins to remove significant amounts of copper from a given volume of etchant without the use of expensive and harmful organic solvents. The amount of copper that can be removed from the etchant is a function of 1) the volume of the treated etchant and / or column size and 2) the specific initial mass flow rate of copper through the column. The etchant and resin are treated by an adsorption and desorption process using ion exchange resins and resin columns. Adsorption and desorption are performed at different flow rates to determine the effectiveness of the resin in removing copper. Copper is desorbed from the resin using a sulfuric acid electrolyte. The process described herein provides a solution to conventional LLE systems that use harmful organic solvents to extract copper ions from etchants and release harmful gases during the treatment process. The use of ion exchange resins provides harmless solids that can be disposed of without causing environmental damage. This demonstrates the advantage of using solvent-free copper extraction with ion exchange resins. The use of resin columns, which have a much smaller footprint than LLE mixers and / or settling tanks, provides an area that can be used for other processes. The resin column also eliminates the risk of cross-contamination between fluids because etchants and acid electrolytes are not used simultaneously, whereas LLE units operate with both liquids in contact. Therefore, the risk of cross-contamination in the resin column is reduced by using water rinsing, air purging, and discarding dilution liquids. Even if cross-contamination occurs in the system of the present invention, for example due to valve failure, the subsequent waste treatment system will be able to handle the resulting waste because the organic phase will be eliminated, i.e., only the aqueous solution will remain. Furthermore, conventional methods focus on removing all ions from the cleaning process, while the process described herein instead focuses on removing only a target number of ions to keep the overall chemistry of the system within certain control limits. Therefore, the system and process of the present invention save time and improve the overall efficiency of the cleaning process. Moreover, the resin system described herein is modular, meaning it can be assembled in many different configurations. Therefore, the system of the present invention can occupy less space compared to conventional LLE systems.

[0015] Therefore, the solvent-free copper extraction process and system described in this article provide a safe and efficient solution for metal extraction technology. Attached Figure Description

[0016] Figure 1 The apparatus for performing the adsorption process is shown.

[0017] Figure 2 The apparatus for performing the desorption process is shown.

[0018] Figure 3 A flowchart describing the adsorption process is shown.

[0019] Figure 4 A flowchart describing the desorption process is shown.

[0020] Figure 5 A flowchart describing the water treatment and resin system is shown.

[0021] Figure 6A and Figure 6B A system for carrying out adsorption and desorption processes is shown.

[0022] Figure 7 A table is shown describing the test plans used for desorption and adsorption at different flow rates.

[0023] Figure 8 A graph depicting the copper concentration levels associated with adsorption is shown.

[0024] Figure 9 A graph depicting the pH curves in relation to pH levels during adsorption is shown.

[0025] Figure 10 A graph depicting the amount of copper removed at a throughput of 3 BV relative to the specific mass flow rate is shown.

[0026] Figure 11 A graph depicting the copper concentration, effluent temperature, and time during the desorption process is shown.

[0027] Figure 12 A table showing desorption times based on the target flow rate is provided.

[0028] Figure 13 A graph comparing desorption time with volumetric flow rate is shown.

[0029] Figure 14 A graph showing the measured amounts of discarded waste generated during adsorption and desorption is presented.

[0030] Figure 15 A table describing the results of the adsorption and desorption processes is shown.

[0031] Figure 16 A graph is shown illustrating the chloride concentration during adsorption relative to the throughput over time.

[0032] Figure 17 A graph depicting ORP relative to time in relation to throughput is shown.

[0033] Figure 18 A graph depicting the proportion relative to time in relation to throughput is shown.

[0034] Figure 19 A graph depicting the copper concentration of different types of copper relative to time is shown.

[0035] Figure 20A table describing the copper and pH fit for adsorption data is shown.

[0036] Figure 21 A table is shown describing the amount of copper removed by etchants ranging from 1 BV to 6 BV.

[0037] Figure 22 A graph depicting the amount of copper removed relative to the amount passed through is shown.

[0038] Figure 23 It is a graph describing the pH of the effluent relative to the throughput.

[0039] Figure 24 A graph depicting the effluent pH relative to the feed concentration is shown.

[0040] Figure 25 A graph depicting chloride concentration relative to time and throughput is shown.

[0041] Figure 26 A graph depicting the concentration of free acid relative to time and throughput is shown.

[0042] Figure 27 A graph depicting sulfuric acid concentration relative to time and throughput is shown.

[0043] Figure 28 A graph describing specific gravity as a function of time and throughput is shown.

[0044] Figure 29 A table describing the desorption time with respect to flow rate is shown. Detailed Implementation

[0045] This document describes a process and apparatus for removing copper ions from an etchant (e.g., an acidic copper etchant) using an ion exchange resin. Ion exchange resins are harmless solids, thus allowing for easy disposal if necessary. The resin system also eliminates the need for organic solvents. The system and method include apparatus for carrying out adsorption and desorption processes. A column of a certain volume can be provided, and this column can be filled with a commercially available ion exchange resin that facilitates the adsorption of copper ions at low pH. The column may not be completely filled to allow for expansion and compaction. The resin can remove significant amounts of copper from a volume of etchant, sometimes larger than the volume of the resin. This process further avoids the use of expensive and harmful organic solvents. The amount of copper that can be removed from the etchant is a function of 1) the volume of the treated etchant and / or the column size and 2) the relative initial mass flow rate of copper through the column. For etchant treatment, copper ions are adsorbed by the resin, which releases protons into the etchant to maintain charge balance. Once the resin is fully loaded, copper ions are removed from the resin using a sulfuric acid electrolyte. The sulfuric acid electrolyte desorbs the copper and leaves the protons in the resin. Equations 3-6 further characterize this adsorption and desorption process. In these equations, R represents the resin. n The term can have a charge, for example, -2.

[0046] Equation 3, Adsorption of divalent copper:

[0047] Equation 4, Adsorption of monovalent copper:

[0048] Equation 5, Desorption of divalent copper:

[0049] Equation 6, Desorption of monovalent copper:

[0050] Figure 1 The adsorption process of the ion exchange resin system and method using resin column 101 is described. Figure 3An exemplary device (shown in the diagram) is described. The internal volume of the resin column 101 can vary. During the adsorption process, the column can be filled with, for example, approximately 0.906 liters of commercially available ion exchange resin (step 301). The device 100 is equipped with a pump 103 to move liquid through the vertically mounted resin column 101. For example, etchant is pumped from feed etchant 104 through the resin column 101 at a predetermined flow rate (step 302). During adsorption, the treated etchant is collected in a second container 102 (step 304). The etchant is initially stored in feed etchant 104 and fed through the resin column 102 by feed pump 103 at a predetermined flow rate. The column is filled with commercially available ion exchange resin, but not completely filled, to allow expansion and contraction during testing. The device 100 is further equipped with a small pump to move liquid through the vertically mounted resin column 101 at a predetermined flow rate. During this adsorption process, copper (e.g., copper ions) is adsorbed by the resin packed in the resin column 102, wherein the resin releases protons into the etchant to maintain charge balance (step 303). The resulting bulk of treated etchant is collected in the bulk treated etchant container 102 (step 304).

[0051] Figure 2 Describing the execution Figure 4 The apparatus for the desorption process involves feeding a sulfuric acid component at a predetermined flow rate into a resin column 201, which is filled with resin that has adsorbed copper ions. The sulfuric acid component is then fed from a container 203 through the resin column 201 at a predetermined flow rate (step 401). The container 203 carries the sulfuric acid component, which is pumped into the resin column 201 to desorb copper. For example, a sulfuric acid electrolyte stored in the container 203 is pumped through the resin column 201 containing resin with adsorbed copper ions. This results in the removal of copper ions from the resin with the sulfuric acid electrolyte, desorbing copper and leaving protons in the resin (step 402). The process may also produce an effluent stream 204, which can be recycled back into the container 203 (step 403). Figure 1 and Figure 2 The devices may be similar in nature, but are described as separate tools that perform each of the adsorption and desorption processes. Figure 1 and Figure 2 The device can be further equipped with an air pump to purge residual liquid from the system between experiments. Temperature and / or pH probes can also be attached to the effluent stream. The flow rates of the etching solution and effluent stream through the resin column can be varied and further used as a function to determine the amount of copper removed.

[0052] Resin columns 101 and 201 have also proven to play an indispensable role in the adsorption and desorption processes related to extraction. Furthermore, resin columns have a significantly smaller footprint than LLE mixers and / or settlers. Resin columns also eliminate the risk of cross-contamination between fluids because etchants and acid electrolytes are not used simultaneously, whereas LLE units rely on simultaneous contact between two liquids. The risk of cross-contamination in the resin column is further reduced by using water rinsing, air purging, and discarding dilution liquids. Therefore, the solvent-free extraction process using the resin columns described herein has proven advantageous compared to conventional extraction methods.

[0053] Figure 5 This is a flowchart providing an overview of the waste treatment and resin system for the adsorption and desorption process. Waste treatment system 501 can treat used rinse water received from resin system 502 and then return clean water to resin system 502. Resin system 502, electrolytic deposition tank 505, and waste treatment system 501 can regenerate etching solution received from etching solution line 506 and one or more etching solution tanks 503 and 504. This etching solution can be stored in regenerated etching solution tank 503 and later sent to etching solution line 506. Etching solution line 506 conveys waste etching solution to waste etching solution storage tank 504, which in turn conveys waste etching solution to resin system 502, where the process restarts.

[0054] In an example embodiment, the system may utilize multiple beds of ion exchange resin contained within media tanks / columns, such as a regenerated etchant tank 503 and a waste etchant storage tank 504. The system may be configured such that a single line of the two tanks / columns 503 and 504 can regenerate sufficient etchant to sustain the etching machine at maximum productivity for one hour. In other embodiments, the etchant may sustain the etching machine for shorter or longer periods, and any number of tanks / columns may be used. Once the first line comprising the two tanks / columns 503 and 504 has completed its processing, it undergoes the regeneration process described above. Regeneration can be achieved by treatment with a regeneration solution. In an example embodiment, the regeneration solution may include, but is not limited to, an acid electrolyte containing a mixture of H2SO4 and copper sulfate. During regeneration within the resin system 502, protons from sulfuric acid received from the electrolytic deposition tank 505 replace copper ions captured by the resin and transported via the etching line 506 from the waste etchant storage tank 504. As a result, the resin is regenerated and the sulfuric acid can be consumed. After desorption, copper can be removed from the sulfuric acid by electrolytic deposition. During the electrolytic deposition process carried out by the electrolytic deposition cell 505, water decomposes at the anode (i.e., the positively charged electrode), producing elemental oxygen, two protons, and two electrons. The electrons travel through an external circuit to the cathode (i.e., the negatively charged electrode) within the electrolytic deposition cell 505, where they then react with a copper sulfate solution received from the resin system 502, resulting in the deposition of solid copper metal on the cathode. The protons then combine with the now-free sulfate anions, thereby regenerating the sulfuric acid consumed during the desorption process. The regenerated sulfuric acid is then returned to the resin system 502.

[0055] In other example embodiments, the cyclic operation process may include additional steps. As a non-limiting example, there may be two or more water rinses and four air purging steps performed by waste treatment system 501. Additionally, an air purging step may be used to remove liquid from tanks / columns 503 and 504, thereby minimizing cross-contamination and dilution of the chemical bath. Water rinsing further minimizes the possibility of cross-contamination between the sulfuric electrolyte and the etching solution. In some example embodiments, due to the slightly acidic nature of deionized water, some copper is extracted from the resin during water rinsing. This copper can be recovered later in the main waste treatment process.

[0056] Figure 6A and Figure 6B This shows further references. Figure 5 The diagram illustrates a system of media tanks and columns for the adsorption and desorption processes. In an example embodiment, the system may include multiple media tanks or columns. These tanks and columns may be arranged in series or parallel and may be distributed throughout the system. For example, as... Figure 6A and Figure 6BAs shown, the system may include six tanks or columns 601, 602, 603, 604, 605, and 606, each containing a bed of ion exchange resin. In other embodiments, the system may include more or fewer tanks or columns. In the illustrated embodiment, the system uses a total of six columns arranged such that there are three parallel groups of two columns connected in series. Each column may hold a predetermined amount of resin, such as, but not limited to, 18 cubic feet of IX resin, but other embodiments may hold more or less IX resin. The system may be configured such that one line of two columns can regenerate sufficient etching solution to sustain the etching machine at maximum productivity for one hour. In an example embodiment, the system may be designed such that while one line (e.g., tanks 601 and 602) is undergoing desorption / regeneration, another line (e.g., tanks 603 and 604) will run the adsorption process. A third line (e.g., tanks 605 and 606) may be used for redundancy purposes to enable full operation even when one of the lines is undergoing maintenance.

[0057] like Figure 6A and Figure 6BAs shown, waste etching solution 640 from the etching machine can be supplied to a spent etch surge tank 610. The waste etching solution from the spent etch surge tank 610 can then be directed to one or more columns, such as columns 601-606. The etching solution can be selectively directed to these columns 601-606 via valves 611 and 612. Additionally, dedicated lines 608 and 609 can be present to direct the etching solution from the spent etch surge tank 610 to one or more columns 601-606 containing resin. The output from columns 601-606 can be selectively directed to one or more output destinations, including one or more other columns, waste treatment systems 616, 617, and 618, a tank 619 for containing regenerated etching solution, an electrolytic deposition buffer tank 620, or an electrolytic deposition pool 621. The output can be directed to each of these destinations via one or more additional selective control valves. The tank 619 for containing the regenerated etching solution can periodically guide the regenerated etching solution 631 to the etching machine pipeline or other etching machine tank. Further, the output is guided to the electrolytic deposition buffer tank 620, and the output of the electrolytic deposition buffer tank 620 can be guided to the electrolytic deposition cell 621. The electrolytic deposition cell 621 can replace the copper ions captured by the resin and guide the regenerated liquid back to columns 601-606 via selective control of valves 613 and 614. Additionally, each column can be associated with air purging 622, 623, 624, 625, 626, and 627, which can direct air into any of the columns 601-606 to facilitate the removal of excess liquid. Additional air purging may be included throughout the system. For example, after the step of treating the etchant in any of the resin columns 601-606 during the adsorption process, once any of the columns 601-606 is fully saturated, excess liquid can be removed using air purging 622-627. Air purging 622-627 will facilitate the removal of saturated etchant from the columns 601-606, whereby the saturated etchant is directed to the etchant tank. Before the output reaches the etchant tank, it can be treated with water from water flushing lines 628, 629, and 630. Excess liquid can also be removed using air purging 622-627 when the output from any of the columns 601-606 is heading to waste outlets 616, 617, and 618, which is then directed to the waste outlet. Furthermore, during the desorption process, excess material can be removed to the acid line using air purging 622-627, where it can be treated with flushing water from water flushing lines 628, 629, and 630. Subsequently, the column can be treated again with air purging 622-627 to remove excess liquid, which is then directed to waste outputs 616, 617, and 618.After this, the adsorption process can be restarted, with the entire process itself repeating.

[0058] Despite Figure 5 , Figure 6A and Figure 6B The tank / column described herein is a media column, but other tank / column embodiments can be used in different configurations of the system of the present invention. As a non-limiting example, the system may use, instead of a media column, the following or other alternatives: packed bed reactor (PBR); fluidized bed reactor (FBR); packed or fluidized adsorption / extraction column configuration; ion exchange membrane (different from ion exchange media beads); batch reactor (BR) or semi-batch reactor (SBR) or fed batch reactor; continuous stirred tank reactor (CSTR); drum or conveyor collection device for resin beads; co-current or counter-current reactor; dedicated filter housing; continuous or batch mix-filter-mix type operation; and portable treatment systems for localized treatment.

[0059] Figure 7 This is a table providing an overview of the details and results of exemplary tests on the adsorption and desorption processes. Specifically, Table 5 shows the results of fourteen adsorption tests and fourteen desorption tests. Fourteen adsorption tests were performed using five different flow rates 701 within the manufacturer's specifications. The same number of desorption tests were run at five different flow rates 702. Unlike adsorption, four of the five desorption flow rates exceeded the manufacturer's specifications. Flow rates were classified into different categories based on rate values, including flow categories 703 described as “low,” “medium-low,” “medium,” “medium-high,” and “high.” Other categories related to flow rate may also be applied. Preliminary tests revealed that the resin can be regenerated more quickly at flow rates exceeding the manufacturer's specifications. Regeneration rate is crucial for the resin's effectiveness in practical applications, therefore, flow rates exceeding specifications during testing are of particular interest. During the adsorption and desorption tests, both the effluent liquid leaving the column and the total liquid collected in the column were aggregated. The flow rate was determined by collecting the effluent sample for a known duration and measuring the volume of the collected liquid. Each time an effluent sample is collected, record the effluent temperature and pH value. Between tests, purge the column with air, rinse with water, and purge with air again.

[0060] For adsorption, the copper concentration, chloride concentration, pH, ORP (oxidation-reduction potential), and specific gravity were measured for all samples. ORP is Cu 2+ Cu 1+ The ratio. For desorption, copper concentration, chloride concentration, free acid concentration, sulfuric acid concentration, pH, and specific gravity are measured. The experimental test plan is shown in Figure 7Table 1 shows that preliminary tests revealed that even with air purging, the resin retained a significant amount of water from the rinsing cycle. This residual water diluted the etchant and electrolyte. To counteract this, the first liquid leaving the column was discarded into a second container. The discard volume for each test was measured.

[0061] Adsorption tests follow the following Figure 8 The copper curves show similar trends, which repeat in each test, with the only variation being the time taken to reach the breakthrough point, e.g., when the effluent copper concentration 801 equals the feed copper concentration 802. The graph depicts the copper concentration during adsorption relative to the throughput over time, and the breakthrough point, e.g., the point where the effluent copper concentration 801 equals the feed copper concentration 802. During the initial adsorption period before returning to near-feed conditions, the chloride concentration decreases slightly, although chloride was not monitored as closely as other measurements due to limitations in laboratory testing. Figure 9 As shown, pH data related to the etching solution were also determined. The pH data depicted in curves 901 and 902 are generally consistent across tests applied at various flow rates during adsorption. A sharp increase in the pH of the solution is expected as copper is removed from the etchant and replaced with protons as determined by equations 3 and 4. This trend generally applies to most cases with different flow rates. A sudden increase in ORP was found during the initial adsorption period in all but one test. This sudden increase in ORP indicates that the resin reacts strongly with Cu. 1+ The affinity is higher than that for Cu 2+ The affinity of the solution was observed. With each test, the ORP stabilized to near the feed conditions. Finally, the trend in specific gravity was consistent between tests. The specific gravity of the solution was expected to decrease due to copper removal. The decrease in specific gravity was significant before approaching the feed conditions.

[0062] In addition, temperature can be monitored to determine the amount of etchant cooled during adsorption in all monitored tests. The collected data indicate the throughput in the bed volume relative to the fluid volume that has passed through the column. The bed volume is the dimensionless volume calculated using Equation 7.

[0063]

[0064] Data of particular interest include, for example, flow rate, copper concentration, and pH level. For instance, Equation 8 is used to calculate copper concentration data.

[0065]

[0066] Where: [Cu] is the copper concentration, t is time in minutes, and B, K, M, and Z are constants.

[0067] The pH curve of the effluent was found to be ( Figure 9The descending portion of (901) fits the linear equation well. Further data summarizing the fit for copper and pH are discussed below.

[0068] A fitted formula for the overall copper concentration was used to calculate approximate amounts of copper to be removed from different total volumes of etchant. The results of these calculations, based on different flow rates, determined the feed copper concentration and the amount of copper to be removed (which was determined and correlated with the flow rate and relative to the etchant volume). The mean and standard deviation of these measurements were evaluated to determine the amount of copper removed relative to the throughput.

[0069] These test results indicate that even when processing the same amount of etchant, different amounts of copper can be removed from the etchant. These differences can be attributed to 1) different volumetric flow rates through the resin and 2) different feed copper concentrations. In ideal test conditions, both the flow rate and the feed copper concentration would be controlled and varied, but the feed concentration varies because the etchant is withdrawn from the running process pipeline. As a result, the experimenter only adjusted the flow rate of the etchant during the experiment. The amount of copper removed from the total was compared with the volumetric flow rate, the feed copper concentration, and the specific inlet mass flow rate of copper. The specific inlet mass flow rate of copper, calculated using Equation 9, takes into account the volumetric flow rate, resin volume, and feed copper concentration.

[0070]

[0071] The data showed the best fit when compared to the specific inlet mass flow rate of the processed etchant in a three-bed volume. Data such as the amount of copper removed and the mass flow rate can vary with changes in the amount of processed etchant. The corresponding collected data are depicted in... Figure 10 The graph shows the amount of copper removed relative to the mass flow rate at a given volume throughput. Figure 10 The graph further illustrates that increasing the feed copper concentration or flow rate will increase the amount of copper that can be pulled out of the etchant (in Figure 10 (Shifting to the right on the graph), while reducing the feed copper concentration or flow rate will result in less copper being removed from the etchant (in... Figure 10 (Move to the left on the curve).

[0072] Furthermore, pH analysis of the effluent can be performed, particularly for measurements of interest to experimenters for control purposes in real-world systems. Effluent pH is determined as a function of the amount of etchant treated and the feed copper concentration. Predicting effluent pH requires a two-step calculation, first determining the bed volume, and then determining the feed concentration.

[0073] Regarding the desorption process, each desorption test follows a similar trend, with the only difference being the time it takes to complete the desorption. Figure 11The copper concentration, effluent temperature, and time for the eluent (e.g., sulfuric acid electrolyte) were plotted. During the experimental tests, each test except one had an effluent copper concentration 1101 passing through a point below the total and / or feed copper concentration 1102. At this point, all copper had been removed from the resin column 201. This point was not captured in test twelve because the sample was not collected close enough to reduce the occurrence of the desorption. The experimenter compared desorption time and volumetric flow rate through the column by manually collecting (e.g., manually reading) the intersection of the effluent versus total copper concentration curves. The desorption time relative to the column volumetric flow rate data is valuable in desorption. For example, Figure 12 Table 4 describes the desorption times 1214 relative to different target flow rates 1211. Flow types 1210 are classified based on the target flow rate 1211. Flow categories included in the table are, for example, “low,” “medium-low,” “medium,” “medium-high,” and “high.” Other terms may be used to characterize flow categories. The table further discloses the time 1214 required for desorption to determine the final copper concentration 1213 based on the flow rate and taking into account the feed copper concentration 1212. Figure 13 A graph showing the changes in time and flow rate required for desorption is presented.

[0074] The temperature of the effluent stream can also be monitored. According to the monitored tests, the temperature of the effluent stream increases as copper is desorbed. Due to limitations of laboratory testing, only the chloride concentration of the overall sample is measured. Each test ends with a final chloride concentration higher than the concentration at the start of the test. During desorption, the free acid concentration decreases as protons remain in the resin and are replaced by copper in the solution, as determined by equations 5 and 6. The total sulfuric acid concentration in the solution decreases slightly in each test, which is unexpected, as this value is generally expected to remain constant throughout the test. The slight decrease is likely a result of some dilution from water trapped in the resin. Additionally, for each test, the specific gravity decreases slightly and then increases with the feed rate. This again indicates some dilution, as the specific gravity of the electrolyte should generally only increase as copper is drawn into the solution.

[0075] When designing a real-world system, it's also important to consider the amount of waste. The amount of water generated during operation must be taken into account, as it can put pressure on the PCB manufacturer's waste management system. This is often applicable to manufacturers operating with zero liquid discharge. Figure 14A graph depicts the values ​​associated with waste generated during desorption and adsorption at various flow rates. Based on these values, the average adsorption value of the generated waste is 0.574 BV, and the average desorption value is 0.27 BV. The main sources of waste generation are discarded diluted etchant and electrolyte. It was found that the initial effluent liquid was significantly diluted by residual water trapped in the resin. During the experimental testing, the amount of discarded waste generated in each test was measured and recorded.

[0076] Analysis of the adsorption data further indicates that there are two steps involved in controlling or predicting the amount of copper removed from the total etchant volume. The first is the resin column (101, 201) size. Given a constant amount of etchant, a large resin column will result in a smaller bed volume of etchant processed by the column. This will result in more copper being pulled from the total. Conversely, given the same etchant volume, a smaller column will result in a larger bed volume of etchant processed by the resin column. Once the column size is set, the initial copper mass flow rate can be adjusted by changing the feed copper concentration or the volumetric flow rate through the resin column. Increasing the feed copper concentration or flow rate will increase the amount of copper that can be pulled from the etchant, while decreasing it will result in less copper being removed from the etchant. This is in… Figure 10 The charts indicate and confirm that the feed concentration depends on how much copper dissolves in the etchant (which is a function of how much is used by the etching machine). Therefore, the inlet mass flow rate can be controlled by adjusting the volumetric flow rate through the resin. Thus, the analysis of the adsorption data further demonstrates that resin 2) is effective in removing copper from the etchant and that 2) is predictable and controllable.

[0077] The desorption process is simpler than the adsorption process. Since the goal of desorption is to remove copper from the resin as quickly as possible, the desorption time plays a valuable role in this process. Results and evaluations of the desorption data demonstrate that the desorption time is valuable relative to the target flow rate. The required desorption time is determined based on the flow rate. Equation 10 uses R = 0.9883. 2 The value determines the desorption time.

[0078]

[0079] The time is measured in minutes, and the flow rate is measured in bed volume per hour.

[0080] As the volumetric flow rate approaches zero, the desorption time approaches infinity. Conversely, when the volumetric flow rate is infinitely fast, the desorption time approaches zero. It was found that the desorption time is only a significant function of the volumetric flow rate, and not of the copper concentration or the free acid concentration.

[0081] like Figure 14As indicated, the amount of waste generated during the desorption process must also be considered. The amount of waste generated from discarding dilute acid and etchant is determined manually and based on the color of the effluent. Desorption data indicates that the acid electrolyte is diluted despite the initial effluent liquid being discarded. Factors to consider include whether sufficient liquid is discarded, thus affecting the collected desorption data points. In most cases, the amount of waste generated during desorption is equal to that generated during adsorption. Similar to the adsorption process, this waste generation must also be considered when designing a real-world waste management system for PCB manufacturers. Waste regeneration and recycling are also important environmental considerations.

[0082] Further details regarding the results of tests conducted on the systems and methods described herein are shown in the attached figures. Figure 15-29 The tables and graphs in the document illustrate further results related to the embodiments described herein. Figure 15 It is a table that provides an overview of the details and results of exemplary tests on the adsorption and desorption processes. Figure 16 It is a graph describing the chloride concentration relative to the throughput over time during adsorption. Figure 17 It is a graph that describes the ORP relative to the time of throughput. Figure 18 It is a graph that describes the proportion relative to the amount of throughput over time. Figure 19 It is a graph depicting the copper concentration of different types of copper relative to time. Figure 20 This is a table describing the copper and pH fit of the adsorption data. Figure 21 This is a table describing the amount of copper removed by etchants ranging from 1 BV to 6 BV. Figure 22 It is a graph describing the amount of copper removed relative to the amount passed through. Figure 23 It is a graph describing the pH of the effluent relative to the throughput. Figure 24 It is a graph describing the pH of the effluent relative to the feed concentration. Figure 25 It is a graph describing chloride concentration relative to time and throughput. Figure 26 It is a graph describing the concentration of free acid relative to time and throughput. Figure 27 It is a graph describing the concentration of sulfuric acid relative to time and throughput. Figure 28 It is a graph describing the specific gravity relative to time and throughput. Figure 29 It is a table describing the desorption time with respect to flow rate.

[0083] The embodiments and collected data disclosed herein further demonstrate that it is feasible to remove copper (including copper ions) from etchants such as acidic copper etchants using ion exchange resins. The resin can remove large quantities of copper from etchant volumes larger than the resin volume and by avoiding expensive and harmful organic solvents. The amount of copper that can be removed from the etchant is 1) the volume of the treated etchant and / or the size of the resin column and 2) a function of the copper flow rate through the column relative to the initial mass flow rate, such as... Figure 10 The data in the graph indicates this. Further calculations show that optimization to remove an additional amount of excess copper from the etchant is possible. The collected data also demonstrate the feasibility of desorbing copper from the ion exchange resin using a sulfuric acid electrolyte. The data further indicate that the time required for copper desorption from the resin is a function of the volumetric flow rate of the acid electrolyte.

[0084] Ion exchange processes have proven well-suited for extraction and are advantageous compared to liquid-liquid extraction, which relies on harmful organic solvents. These solvents are expensive, require frequent metering, and incur significant disposal costs, especially when dealing with thousands of liters of hazardous liquids. Ion exchange resins provide safe and harmless solids that can be disposed of without environmental damage if necessary. This has proven to be a significant benefit of using ion exchange resins for solvent-free copper extraction. Furthermore, while the systems and processes described herein focus on copper removal, it should be understood that these systems and processes can be used to remove other metals or substances, or indeed for other purposes. In exemplary embodiments, the systems and processes described herein can be used to target the removal of contaminating metals from a chemical bath (i.e., the removal of contaminating iron from an electroplating bath); to target the removal of harmful compounds to protect other processes (i.e., the removal of halogens prior to the electroplating process); and to regenerate other chemical baths for reuse without having to completely rebuild the bath.

Claims

1. A method for removing copper from an etchant, the method comprising: Copper extraction based on resin, wherein the amount of copper removed from the etchant is a function of the volume of the etchant being treated, based on the size of the resin column, and the initial mass flow rate of copper through the resin column. The extracted copper is desorbed from the resin using a sulfuric acid electrolyte; and Determine the effectiveness of extracting the copper from the etchant.

2. The method as described in claim 1, wherein, Extracting the copper includes: The etchant is used to adsorb copper ions and release protons into the etchant to maintain charge balance.

3. The method as described in claim 1, wherein, The extracted copper is desorbed, including: When the resin is fully loaded, copper ions are removed, while protons are retained in the resin.

4. The method of claim 1, wherein, The type of resin is selected based on at least one factor related to pH value, which is relevant to the adsorption of copper ions.

5. The method of claim 1, wherein, The flow of copper through the resin column is based on a small pump.

6. The method of claim 5, further comprising: The resin column is treated by air purging, water rinsing, and then air purging again.

7. The method of claim 4, wherein, The removal of copper ions and the maintenance of protons increase the pH of the solution.

8. The method of claim 4, wherein, The solution decreases due to gravity in response to the removal of the copper.

9. The method of claim 1, wherein, The temperature of the etchant decreases during adsorption.

10. The method of claim 1, wherein, The amount of copper removed from the etchant is based on the volumetric flow rate through the resin and the feed copper concentration.

11. The method of claim 1, further comprising: The inlet mass flow rate of copper is determined based on a value corresponding to the volumetric flow rate, the volume of the resin, and the feed copper concentration.

12. The method of claim 1, wherein, The time required to desorb the extracted copper from the resin is a function of the volumetric flow rate of the sulfuric acid electrolyte.

13. The method of claim 1, wherein, The etchant is formed from copper chloride.

14. The method of claim 1, wherein, The amount of copper removed is calculated using the following formula: 。 15. An apparatus comprising: A feed etchant container for storing etchant; A resin column for storing resin, wherein the amount of resin is less than the volume of the resin column; A feed pump for pumping the etchant from the feed etchant container through the resin column at a predetermined flow rate; Copper ions are adsorbed from the etchant by the resin stored in the resin column; Protons are released into the etchant through the resin; as well as A treated etching solution container for collecting the etchant from the resin column.

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