WO2011150532A1

WO2011150532A1 - System and method for recovering spent etching solution

Info

Publication number: WO2011150532A1
Application number: PCT/CN2010/000787
Authority: WO
Inventors: Sadok Nehdi
Original assignee: Kuttler Automation Systems (Suzhou) Co., Ltd.; Wuxi Suntech Power Co., Ltd.
Priority date: 2010-06-03
Filing date: 2010-06-03
Publication date: 2011-12-08
Also published as: CN103025667A

Abstract

A system for recovering a spent etching solution is provided. The system including an etching device which is used for producing the spent etching solution in an etching reaction, an oxidation device which includes a first processing section for removing ammonia from the spent etching solution and a second processing section for oxidizing the spent solution passed from the first processing section, a regeneration device for regenerating the spent etching solution passed from the second processing section and an electrolysis device for plate out copper from the spent solution passed from the second processing section. At the same time, a method for recovering a spent etching solution is provided. The spent etching solution, by the system and method, can be recovered up to almost 100%.

Description

SYSTEM AND METHOD FOR RECOVERING SPENT ETCHING SOLUTION

TECHNICAL FIELD

The present invention relates to etching technology, more particularly, to a recovering process for spent etching solution . BACKGROUND

As well known, in metal etching industry they of en have resort to chemical etching processes.

For example, this is the case with electronic industry in the production of printed boards. In an etching machine or line, an active etching solution comprising ammonia chloride and small percentage of other chemical agents is introduced to suitable continuous baths. The copper assemblies are dipped into the baths and its portion made up of the thin copper sheet provided on them is removed from the same through selective etching resulting from chemical attack carried out by the solution, such that the formation of conductive paths according to a previously established topography , i.e. electric c i rcui ts , is obtained.

With the traditional process to treating printed circuit boards, the panels are processed with the etching solution. The removal of the copper on the printed circuit board is temporally limited and partially completely blocked with Sn, Ag or other metal or plastic alloys to build the conductors.

Usually a removal of copper at a rate of 60 μχχ\ per minute can be achieved. The conventional alkaline etching solutions have to be continuously replaced either by fresh or recycled etching solution, whereas the rinsing water and the exhaust gases might not or only partially be recycled which is undesirable .

Thus it is necessary to create a process and a system to accomplish the process, with the objective to recycle the etching solution and reuse it simultaneously in the etching machine by a simple , efficient and economical method in a closed loop . In addition the exhaust gases produced during the complete process as well as the rinse water of the etching machine contaminated with etching solution shall be treated and recovered up to 100% in a closed loop to reduce cost and avoid pollution .

SUMMARY OP THE INVENTION

According to one aspect of the present invention, there is provided a system for recovering a spent etching solution, including : an etching device, used for an etching reaction, the etching reaction producing the spent etching solution; an oxidizing device, including:

a first processing section connected to the etching device, used for receiving the spent etching solution passed from the etching device, the first processing section extracting ammonia gas from the spent etching solution; and a second processing section connected to the first processing section, used for oxidizing the copper ion in the spent solution passed from the first processing section; a regenerating device connected to the second processing section, used for increasing the concentration of the copper complex and adjusting the PH value of the spent etching solution which is passed from the second processing section, the spent etching solution with the increased concentration of the copper complex and the adjusted PH value being passed to the etching device to serve as an etching solution; and an electrolyzing device, including: an electrolyzing unit connected to the fist processing section, used for plate out the copper from the spent solution which is conveyed from the first processing section; an intermediate tank connected to the electrolyzing uni , receiving the spent solution with reduced cooper

concentration from the electrolyzing unit; wherein the ammonia gas extracted from the first processing section is passed to the second processing section, the gases escaped from the second processing section are passed to the regenerating device, and the gases escaped from the regenerating device are passed to the first processing section; and wherein a gases escaped from the etching device, the electrolyzing unit, and the intermediate tank are passed to the second processing section.

Preferably, the etching device includes a spray unit for spraying the etching solution, a solution tank for storing the spent etching solution, and a rinsing unit to clean an etched circuit board.

Preferably, the first processing section includes a first processing unit connected to the etching device, a second processing unit connected to the first processing unit, as well as a third processing unit connected to the second processing unit, such that the spent etching solution flows from the first processing unit to the third processing unit through the second processing unit; and the second processing section includes an oxidizing unit connected to the third processing unit and a oxidizing completing unit which is connected to the oxidizing unit, such that the spent etching solution is conveyed from the third processing unit to the oxidizing completing unit through the oxidizing unit.

Preferably, the second processing unit includes a first processing sub-unit and a second processing sub-unit, wherein a circuit is formed among the first processing sub-unit₍ the second processing sub-unit and the third processing unir..

Preferably, the spent etching solution flows in the circuit for three cycles before the spent etching solution is conveyed to the oxidizing unit.

Preferably, ammonia gas is extracted from the first processing unit, the first processing sub-unit, and the second processing sub-unit, and the extracted ammonia gas is passed to the oxidizing completing unit.

Preferably, gases escaped from the oxidizing unit are passed to the completing oxidizing unit.

Preferably, gases escaped from the etching device, the electrolyzing unit, and the intermediate tank, are passed to the oxidizing unit.

Preferably, wherein the regenerating unit includes a first regenerating unit for adjusting the PH value of the spent etching solution in the range from 8.2 to 8.6 and a second regenerating unit for increasing the concentration of the copper complex [ Cu ( NH₃ ) ₄ ] ¹ ' in the spent etching solution passed from the oxidizing completing unit.

Preferably, gases escaped from the first regenerating unic are passed to the second regenerating unit.

Preferably, an injector is used to suck out of the gases which are not dissolved in the second regenerating unit and re-inject into the spent etching solution in the second regenerating unit.

Preferably, the second regenerating unit is connected to the first processing unit, to make the spent etching solution in the second regenerating unit conveyed to the first processing unit when the etching device does not work.

Preferably, 0.6% to 0.9% of the spent etching solution volume coming from the etching device is conveyed to the electrolyzing unit. Preferably, the spent solution in the intermediate tank is passed to the oxidizing unit.

Preferably, the system further including a gas processing device which extracts ammonia gas out of the gases escaped f om the third processing unit and transfers the extracted ammonia gas to the oxidizing completing unit.

Preferably, the gas processing device includes a condensator, a scrubber, and a separating unit, wherein: the condensator receives the gases escaped from the third processing unit and separates ammonia gas from said gases by means of condensation, and said ammonia gas is passed to the oxidizing completing unit; the scrubber receives the remaining gases in the condensator and scrubs these gases in a solution in the scrubbe , part of the solution of the scrubber comes from the rinsing unit, and said solution is passed to the oxidizing unit; the separating unit receives the condensate from the condensator, and receives gases passed from the scrubber as well as separates ammonia gas from said gases, and the separated ammonia gas is passed to the first regenerating unic.

Preferably, the separating unit includes a first:

separating sub-unit and a second separating sub-unit, zhe second separating sub-unit receiving the condensate conveyed from the condensator and releasing the ammonia gas contained in the condensate by means of a reduced pressure , the condensate then being conveyed to the first separating sub-unit from the second sub-unit, the first separating sub-unit receiving the gases from the scrubber and the condensate therein absorbing the gases by means of a increased pressure , the condensate with the absorbed gases from the scrubber in the first separating sub-unit being conveyed back to the second separating sub-unit . Preferably, the separating unit further includes a third separating sub-unit which receives the condensate conveyed from the second separating sub-unit and extracts the ammonia gas contained in the condensate .

Preferably, the gas processing device further includes a neutralizer which contains a neutralizing solution for neutralizing the excess gases passed from the separating unit; and the neutralizing solution is passed to the scrubber.

Preferably, the system further includes a water process device to recover a rinsing solution of the rinsing unit.

Preferably, the rinsing unit further includes a first rinsing sub-unit , a second rinsing sub-unit , and a third rinsing sub-unit .

Preferably, the water process device includes a first tank, a second tank, a third tank and an osmosis unit, wherein: the first tank receives the solution conveyed separately from the separating unit and the osmosis unit, as well as supplies the mixed solution to the first rinsing sub-unit, the second rinsing sub-unit, and the third rinsing sub-unit; the second tank receives a solution from the second and chird rinsing sub-units and supplies it to the osmosis unit; the osmosis unit processes the solution supplied from the second tank to obtain pure water to be conveyed to the third tank; and the third tank stores the pure water and supplies them to the third rinsing unit when the salt concentration in the third rinsing unit is more than a preset value.

Preferably, the first tank receives the solution conveyed from the third separating sub-unit and the osmosis unit.

According to ano her aspect of the present invent ion, here is provided a method for recovering a spent etching solution, including:

a) extracting an ammonia gas from the spent etching solution which is contained in a first processing section of an oxidizing device ;

5 b) conveying the spent etching solution after the extraction of the ammonia gas in the first processing section to a second processing section of the oxidizing device; c) oxidizing the copper ion of Cu^* of the spent solution to be ion of Cu" with the ammonia gas extracted from the spent

10 etching solution in the first processing section according to the [Cu(NH₃)₂ + NH₃ + NH + 1/4 0₂ —[Οι(ΝΗ₃)₄Γ^* + l/2H₂0 in the second processing section; d) conveying the spent etching solution which is oxidized to a regenerating device to increase the concentration of lb [Cu (NH₃) J ' ' of the spent etching solution from the second processing section, and stabilizing the copper complex

[Cu (NH₃ ) ₄] and the PH value of the spent etching solution; e) conveying the spent etching solution with increased concentration of [Cu (NH₃ ) ₄] '⁺ and stabilized PH value in the 20 regenerating device to an etching device to serve as an etching solution .

BRIEF DESCRIPTION OF THE DRAWINGS

FIG.l schematically shows one example of system for recovering the spent etching solution according to the present b invention;

Fig.2 schematically shows another example of the system for recovering the spent etching solution according to the present invention;

Fig .3 schematically shows yet another example of the system 30 for recovering the spent etching solution according co the present invention; Fig. shows the variation of the chemical potential depending on the concentration of ammonia;

Fig.5 shows the flow diagram of the method of recovering a spent etching solution according to the present invention;

Fig.6 shows the flow diagram of the gases process of the gases escaped from the third processing unit 50d; and

Fig.7 shows the flow diagram of the procedure for the water process device.

DETAILED DESCRIPTION

Before the present invention is described, it is to be understood that this invention is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the term used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

Briefly described, the present invention provides an approach that the spent etching solution can be efficiently recovered and the chemical agents, such as ammonia and the water, in the spent etching solution can be almost fully reused.

In the following description, the term "liquid connecting pipe¹¹ refers to a pipe through which the liquid can be passed; the term "^"gas connecting pipe ¹¹ refers to a pipe through which the gas can flow. Moreover, in the detailed description thac follows, like element numerals are used to describe like elements illustrated in one or more figures.

These and other objects, advantages, and features of the invention will become apparent to those persons skilled in the art upon reading the details of the invention as more fully described below.

Fig.l schematically shows one example of the system for recovering the spent etching solution according to the present invention. As shown in Pig.l, the system for recovering the spent etching solution includes an etching device 10, an oxidizing device 50, a regenerating device 60, and an electrolyzing device 70.

with reference to Fig.1, a spraying unit 30 of the etching device 10 sprays the etching solution to the electric circuit board such as a Printed Circuit Board (PCB) ; thus a chemical reaction between the etching solution and the electric circuit board takes place. A solution tank {not shown in the figures) is used to contain the resulting solution , i.e. the spent etching solution which generally includes various chemical agents such as ammonia, carbonate such as copper carbonate, ammonium phosphate, ammonium sulphate , nickel sulfate , copper sulfate, and water. The etching device 10 further includes a rinsing unit 80, which includes a first rinsing sub-unit 80a, a second rinsing sub-unit 80b, and a third rinsing sub-unit 80c, used to clean the printed circuit board which has been etched, a rinsing solution used for clean the circuit board is included in the rinsing unit and the salt concentration of the rinsing solution can be adjusted to make it be suitable for cleaning the printed circuit board. Said board is firstly cleaned in the first rinsing sub-unit 80a where the solution comes from the second rinsing sub-unit 80b, then cleaned in the second rinsing sub-unit 80b where the solution comes from che third rinsing sub-unit 80c, finally cleaned in the third rinsing sub-unit 80c which receiving the water from the third tank 420.

The oxidizing device 50 includes a first processing section and a second processing section, wherein the first processing section receives the spent etching solution conveyed from the solution tank through a liquid connecting pipe 100. It should be understood that the spent etching solution can be continuously sent to the first processing section, and also can be sent to the first processing section when the volume of the spent etching solution in the solution tank reaches a preset volume . Af er extraction of ammonia gas from the received spent solution in the first processing section, the spent solution with reduced concentration of ammonia gas is conveyed to the second processing section. Said extraction of ammonia gas is accomplished by reducing the pressure applied on the spent solution to 0.5-0. atm. With reduced concentration of H_j, stability of the copper complex [Cu(NH₃)₂]^T in the spent etching solu ion is increased. Inthe second process ing sec ion, the copper complex [Cu(NH₃)₂]^* of the spent etching solution is oxidized to be [Cu(NH₃)J by the injected oxygen and ammonia gases .

Most of the spent etching solution in the first processing section, around 99.1% to 99.4%, is conveyed to the second processing section after the extraction of ammonia gas , whereas the remaining spent solution is passed to the electrolyzing device 70 through a liquid connecting pipe 110 so as to obtain the metallic cooper out of the spent etching solution. The electrolyzing device 70 includes an electrolyzing unit 70a and an intermediate tank 70b, wherein the electrolyzing unit 70a is used to plate out the metallic copper f om the spent solution to reduce the copper ion concentrat on and the intermediate tank 70b stores the spent solution with a reduced copper ion concentration which flows from the electrolyzing unit 70a via a drain pipe 9.

The first processing section of the oxidizing device 50 further comprises a first processing unit 50a, a second processing unit having a first processing sub-unit 50b and a second processing sub-unit 50c, as well as a third processing unit 50d. The second processing section includes an oxidizing u it 50e and an oxidizing comple ing uni 5 Of . As shown in Fig. l, the spent etching solution is firstly conveyed to the first processing unit 50a via the pipe 100 and there is an operation of extraction of ammonia gas in the first processing unit 50a by for example an extraction pump in order to stabilize the copper complex [Cu{NH₃)₂j wherein the spent etching solution in the first processing unit 50a generally includes ( NH, ) ₂ SO,, NH.Cl, (NH₄) ,P0_4/CuS0_4>CuC0_3# NH₃ / ΝΗ,ΟΗ, etc..

The spent etching solution, after further extraction of the ammonia gas in the first process sub-unit 50b, is then conveyed to the second process sub-unit 50c to remove the ammonia gas again. Typically, the extraction of NH₃ from the spent solution in the first processing sub-unit 50b and second sub-unit 50c is performed by reducing the pressure to 0.5-0.9atm.

Thereafter, the spent solution flows to the third processing unit 50d from the second sub-unit 50c. With reduced concentration of ammonia gas, the spent solution in the third processing unit 50d has more capacity to absorb the excess gas which is conveyed by a gas connecting pipe 300 from the regenerating device 60, where the excess gas includes the ammonia and air. An injector can be used to make said excess gas dissolved in the spent solution of the third processing unit 50d. It is preferred that the pressure applied in the third processing unit 50d is at the range from l.Olatm to 1.05atm.

The spent solution which absorbs said excess gas is conveyed back to the first processing sub-unit 50b, in which the extraction of the ammonia gas is performed, and then conveyed to the second processing sub-unit 50c to remove the ammonia gas. After the ammonia gas extraction in the first and second processing sub-units 50b and 50c, the spent solution subsequently flows to the third processing unit 50d.B'or the purpose of extracting the ammonia gas in the spent etching solution as far as possible and making t e spent etching solut ion in the third processing unit 50d absorb more gas, especially NH₃ produced in the regenerating device 60, a circuit is formed among the first processing sub-unit 50b, the second process ing sub-unit 50c and the third processing unit 50d. It is preferred that the spent solution, before entering into the second processing section, flows in the circuit for several cycles to make the concentration of the ammonia gas to be around 2g/L through the extraction operation during flowing in the circui , where the number of the cycles depends on the amount of the solution and so on.

After the foregoing extraction of the ammonia gas, the spent etching solution enters into the oxidizing unit 50e of the second processing section of the oxidizing device 50. I is desired that the spent etching solution can pass from the third processing unit 50d and enter into the oxidizing unit 50e under a pressure with the range from l.Olatm to l.05atm. The oxidizing unit 50e also receives the solution conveyed from the intermediate tank 70b via a liquid connecting pipe 120, i.e., the spent solution in the oxidizing unit 50e is the mixture of the solution from the intermediate tank 70b and the spent solution from the third processing unit 50d. The atmospheric oxygen from the etching device 10 is conveyed to the oxidizing unit 50e through a gas connecting pipe 210; and the pure oxygen and ammonia gas from the electrolyzing unit 70a and the intermediate tank 70b are conveyed to the oxidizing unit 50e through a gas connecting pipe 220, and a gas connecting pipe 230, respectively. To ensure that the gases, especially the ammonia gas, are almost totally dissolved in the solution, an injector can be used to inject said gases into the oxidizing unit 50e, where the injector sucks out of the gases at a rate of 10-15m³/h. Moreover, the spent solution flows into the unit 50e at a rate of 9-18m³/hand the pressure applied on the oxidi ing unit 50e would be in the range from l.Olatm to 1.05atm.

In the oxidizing unit 50e, the following chemical reaction takes place to convert Cu^* to C ^{^} :

[Ου(ΝΗ₃)₂]⁺ + NH₃ + NH + 1/4 0₂ —{Cu(NH₃)J" + 1/2H._;,0 Therefore, taking as an example, in order to oxidize about 1 gram of [Cu (ΝΗ₃) ₂] ^* , about 0.17 gram of NH₃ , about 0.18 gram of NH,',and about 0.08 gram of 0₂ are needed. That is, the [Cu (NH₃) _?] \NH_j , NH„ ' and 0₂ would be in the ratio about 100:17:18:8 for taking this chemical reaction. In another example of the present invention, the ammonia gas for this reaction can be obtained by separation thereof from the gases escaped f om the third processing unit 50d.

Then, the spent solution is conveyed from the unit 50e to the oxidizing completing unit 50f and the gas escaped from the unit 50e also flows to the unit 50f through a gas connecting pipe 260. Optionally, an air valve is set between the oxidizing unit 50e and the oxidizing completing unit 50f , which will open when the pressure in the unit 50e is above 1.05atm.^'

Moreover, the ammonia gases extracted from the first processing unit 50a, the first processing sub-unit 50b, and the second processing sub-unit 50c are also directly passed into the oxidizing completing unit 50f . In order for the solution in the oxidizing completing unit 50f to dissolve more ammonia gas, the spent solution is preferably injected to the oxidizing comple ing unit 5 Of under an inj ec ing pressure between l .05 tm to 1.2atm. The quantity of ammonia gas in the solution of the oxidizing completing unit 50f is more than lOg/L. In the unit

50f , the oxidizing reaction is completed and the catalyst can be dosed to the etching solution as per the following chemical reaction :

2 [Cu (NH₃) J ^T + 2NH₃ + 2 (NH„ ) " + 1/2 0₂ — 2 [Cu ( NH₃ ) , ] " + H_;0 According to the present invention, around 0.6% to 0.9% of the volume of the spent etching solution in the first processing unit 50a is conveyed to the electrolyzing unit 70a. Since the extraction of ammonia gas has been done in the first processing section of the oxidizing device 50, the yield of the copper plating out in the electrolyzing unit 70a is improved and push the following reaction in a desired direction:

[Cu{NH₃)₄] " + 2e^" -€u + 4NH₃ CD

2[Cu(NH₃)₂]^* + 2e^" — 2Cu + 4NH₃ ® 20H^" -»l/2 0₂ + H₂0 + 2e^~ ®

[Cu(NH₃).]^*V [Cu(NH₃)₂P + 20H^" Cu + 4 NH₃ + 1/20^ ©

Where the chemical reactions shown as equation (i) and (¾) are a cathodic reaction, the chemical reactions shown as equation (3) is an anodic reaction, and the chemical reaction shown as equation © is fostered if the dissolved NH₃ is reduced whereas the chemical reaction is fostered in a revere direction if the dissolved NH₃ or 0₂ is increased.

After the process of the oxidizing completing unit 50f, the spent etching solution is passed to the regenerating device

60 through a liquid connecting pipe 130, and the gases escaped from the unit 50f also flows to the generating device 60 through a gas connecting pipe 270. An air valve can be set between the oxidizing completing unit 50f and the regenerating device 60 for controlling the gas connecting pipe 270 to be on or off. According to the present invention, the air valve will open when the pressure in the oxidizing completing unit 50f is above 1.2atm. Optionally, a microfilter can be used to filter che spent solution before the spent solution is passed to the regenerating device 60.

The regenerating device 60 for making the spent etching solution ready for reemployment includes a first regenerating unit 60a and a second regenerating unit 60b, wherein the f irsn unit 60a receiving the passed spent solution as well as the gases from the oxidizing completing unit 50f , and the second unit 60b receives the spent solution which has been processed in the first unit 60a.

With the injected gases including ammonia gas and oxygen, the quant i ty of copper complex [Cu (NH₃) ,] ^* in the spent solution is increased in the first unit 60a upon the following reactions :

(Cu(NHj)j]^{' →} Cu^* + 2NH₃;

Cu^* + 2NH₃ + 2NH₄ + l/20_s - Cu^** + 4NH₃+H₂0;

Cu" + 4NH₃ → [Cu(NH₃)J^** It should be understood that in practice the reaction of "Cu^rT + nNH₃ ^→ [Cu (NH₃) J " " takes place in the unit 60a, wherein n is an integer selected from 1,2,3,4 and 5 , The in ected gases comes from the oxidizing completing unit 50f , and the ammonia gas can be injected additionally when the ammonia gas in said gases can not meet the requirement of these reaction. According to a yet another example of the present invention, the NH, needed in the above reactions is obtained by means of separating the pure ammonia gas from the gases escaped from the third process ing unit 50d.

Then the solution is conveyed from the first regenerating unit 60a to the second unit 60b to stabilize the copper complex [Cu (NH₃) J ^T* and to make the PH value be stabilized be ween 8.2-8.6 according to the following reaction;

NH₃ + H₂0 ^ ^' NH₄ ⁺ + OH^"

And the copper complex, formed with the ligand NH, according to the following reaction,, is stabilized through the gases escaped from the first unit 60a.

[Cu(H-0)_n]" + nNH, <=> [Cu(NH_j)_a]^tf + nH₂0

It is preferred that in the second regenerating unit 60b, an injector can be used to suck out of the gases which are not dissolved in the spent solution thereof and re-inject the sucked gases to the spent solution so as to make more ammonia gas dissolved in the spent solution of the second unit 60b.

The solution which has experienced the process in the oxidizing device 50 and the regenerating device 60 is ready for reemployment in the etching process . Therefore the solution in the second regenerating unit 60b can go to the spray unit 30 through a liquid connecting pipe 140 to serve as etching solution. The gases, which escape from the second unit 60b, are passed to the third processing unit 50d to be absorbed by the spent solution with reduced ammonia concentration, in the third processing unit 50d , and then be washed by flowing in the circuit formed among the third processing unit 50d, the first processing sub-unit 50b₍ and the second processing sub-unit 50c for such as three cycles. It can be seen that the regenerating device also serves as a tank for temporary storage of the solution besides serving as a device where the copper complex of the spent solution is increased and the PH value of the spent solution is adj usted to be in the range of 8.2-8.6.

The second regenerating unit 60b is connected to the first processing unit 50a. Accordingly, the ready- for reemployment solution in the second regenerating unit 60b is conveyed to the first processing unit 50a when the etching device 10 does not etch.

Fig.2 schematically shows another example of the system for recovering the spent etching solution according to the present invention. A gas processing device is added and used to separate the ammonia gas out of the gases which are escaped from the third processing unit 50d compared to the system shown in the Fig.l.

The gas processing device includes a condensator 170, a separating unit 180, a scrubber 190 and a neutralizer 20. The condensator 170 receives the exhausted gases escaped from the third processing unit 50d, which includes the ammonia gas and the air which are not utilized in the second generating unit 60b, through the gas connecting pipe 310. In the condensator 170, the ammonia can be separated from the gases by for example reducing the temperature to be below ICC, and the separated ammonia gas goes towards the top of the condensator 170 since its density is less than the other gases', whereas the other gases without separated ammonia go to the bottom of the condensator 170. The separated ammonia gas is passed into che oxidizing completing unit 50f through a gas connecting line 340 so as to oxidize cu' to Cu", and the other gases in bo c com of the condensator 170 flow through a gas connecting pipe 350 to the scrubber 190 where the solution in the scrubber 190 comes from the first rinsing sub-unit 80a and the neutralizer 20. The rinsing solution in the first rinsing sub-unit 80a is the most polluted one because it is the first cascade to clean the etched electric circuit board; and the rinsing solution in the first rinsing sub-unit 80a is conveyed to the scrubber 190 via a liquid connecting pipe 430 when the salt concent rat ion reaches 50% of that of the spent etching solution in the etching device 10.

In the scrubber 190, the following chemical reaction takes place :

[Cu(NH,) , ΝΗ,) ^,iTrr2) + NH₃ — [Cu(NH₃)_nr⁺ + mNH,'

NH₃ + H' — NH

Then the resulted solution in the scrubber 190 is supplied to the oxidizing unit 50e via a liquid connecting pipe 440 to make up for the water lost by evaporation and to enrich the solution with the ion of NH₄' requi ed for the oxidation reaction, whereas the exhausted gases escaped out of the solution in the scrubber 190 is passed to the separating unit 180 through a gas connecting pipe 360. As an example, the gases escaped from the scrubber 190 can be injected into the separating unit 180 by a flow injector.

The separating unit 180 comprises a first separating sub-unit 180a, a second separating sub-unit 180b, and a third separating sub-unit 180c. The condensate in the condensator 170, which comprises the water and the gases from the third processing unit 50d other than the extracted ammonia gas, is transferred to the second separating sub-unit 180b through a connecting pipe 510 andwill re lease the dissolved ammonia gas due to an aspir t ion which reduces the pressure of the sub-unit 180b. Then the released ammonia gas is injected into the first regenerating part 60a through a gas connecting pipe 380. The condensate in the second separating sub-unit 180b is conveyed to the first separating sub-unit 180a via a pipe 520 in order to absorb the gas coming from the scrubber 190 via the pipe 360. It is preferred that a pump is installed in the separating unit 180 to make the condensate circulate between the second separating sub-unit 180b and the firs sub-uni 180a with a pressure of 1.05-1.2atm, such that: the solubility of gases which comes from the scrubber .190 in the solution of the separating sub-unit 180a is increased.

After circulating between the second separating sub-unit 180b and the first sub-unit 180a for a certain number of cycles, where the number of cycles depends on the supplying rate of the condensate from condensator 170, the condensate, i.e. the solution in the second sub-unit 180b, is fed to the third separating sub-unit 180c for a further ammonia gas extraction, and then is passed to a water tank. The ammonia gas extracted by the extraction performed in the separating sub-unit 180b and 180c goes to the first regenerating unit 60a through the gas pipe 380 to contribute to the chemical reaction taking place in the first regenerating unit 60a, and the excess gases which are not dissolved in the solution of the first sub-unit 180a escape from the first separating sub-unit 180a to the neutralizer 20 through a gas pipe 370 for the final treatment before they goes out of the recovering system of present invention. It can be understood that an environment with low pressure should be formed in the second separating sub-unit 180b and third separating sub-unit 180a so as to extract more ammonia gas, and an environment with high pressure should be formed in the first separating sub-unit 180a to dissolve more gases from the scrubber 190.

In the neutralizer 20 , there are chemical reactions between a minim amount of the ammonia gas and the solution which contains 5-15% of sulfuric acid, as follows:

H₂SO„ + 2NH₃ — (NH₄)₂S0₄

H_j + H' — NH₄ ^*

According to the present invention, the solution in the scrubber 190 is conveyed to the oxidizing unit 50e, thereby compensating the lost water in the oxidizing unit 50e and enriching the NH of the solution in the unit 50e. The injection of ammonia gas into the spent etching solution will increase the difference between the chemical potentials of the oxidation pairs Cu++/Cu+ and Cu+/Cu as indicated in figure 4, which supports the etching and improves the production efficiency as well as the production quality of the reaction [Cu {NH.) ..] " + Cu —■ 2 [ Cu ( H₃ ) ₂1 ^* ) · The extraction of ammonia gas from the etching solution fosters the electrolysis process by increasing the due potential difference of the oxidation pairs Cu"/Cu^T and Cu^T/Cu as indicated by figure 4.

Fig .3 schematicall shows yet ano her exampl of the sys em for recovering the spent etching solution according to the present invention. A water process device is additionally provided based on he system shown in Fig.2, which is set be een the etching device 10 and the gas process device, thereby forming a water recovering process road in the system.

With reference to Fig.3, the condensate from the third separating sub-unit 180c, is conveyed to a first tank 400 through a liquid connecting pipe 530. And the rinsing solution, which is passed separately from any of the second rinsing sub-unit 80b and the third rinsing sub-unit 80c to a liquid pipe 450 if the salt concentration of the solution therein is above 1 gram per liter, is conveyed to a second tank 410, wherein the solution flows from the second rinsing sub-unit 80b to the pipe 450 by a sub-pipe 450b and from the third rinsing sub-unit 80c to the pipe 450 by a sub-pipe 450c.

The rinsing solution in the second tank 410 then is passed through a liquid pipe 460 to the osmosis unit 390 where pure water is obtained by the osmosis operation. The obtained pure water is conveyed to a third tank 420 through a liquid pipe 470, and the water in the third tank 420 is continuously passed through a liquid pipe 500 to the third rinsing sub-unit 80c. The remaining solution in the osmosis unit 390 is conveyed to the first tank 400 through a liquid pipe 480 where the conveyed solution is mixed with the solution passed from the third separating sub-unit 180c. When the salt concentration in one of the fist rinsing sub-unit 80a, the second rinsing sub-unit 80b, the third rinsing sub-unit 80c exceeds the preset value such as lg/L, the resulting mixture solution in the first tank 400 is fed to the fist rinsing sub-unit 80a, the second rinsing sub-unit 80b, and the third rinsing sub-uni 80c through a liquid connecting pipe 490a, 490b and 490c, respec ively, so as to adjust the concentration of the salt in the rinsing solution. The rinsing solution in the third rinsing sub-unit 80c can f low to the second rinsing sub-unit 80b. Since the solution in the water process device can flow to and from the rinsing unit 80, the solution in the scrubber 190 is updated based on the liquid connecting pipe 430.

With reference to Pig .4 , which shows the chemical potential depending on the concentration of ammonia gas, the dot line represents the variation of the chemical potential of che oxidation pairs Cu+/Cu, and the solid line represents che variation of the chemical potential of the oxidation pairs Cu++/Cu+. It can be seen that the chemical potential of the spent solution in the oxidizing device 50 is above that in the regenerating device 60, wherein the chemical potential in the regenerating device 60 is enough small to make the spent solution in the regenerating device 60 be stable. However, the chemical potential of the solution in the unit 50c, 50b, 50a, and 50d gradually becomes small, thereby makes the chemical reaction of converting the Cu+ to be Cu++ to be easy.

Fig.5 shows the flow diagram of the method of recovering a spent etching solution. The method of recovering a spent etching solution will be illustrated in the following with reference to Fig.5 and Fig .3.

After the spent etching solution is conveyed to che first processing section of the oxidizing device 50, the extraction (step 500) of the ammonia gas from the spent etching solution is operated by means of reducing the pressure in the first; processing section, such as reducing the pressure to the range from 0.5 atm to 0.9atm. With the reduced concentration of NH₃, the stability of the copper complex [Cu{NH₃)₂]^T of the spent etching solution is increased. Then a portion of the spent solution, which is around 99.1% to 99.4% of the spent etching solution in the first processing section, is conveyed {step 501) to the second processing section. The copper complex [Cu(NH₎)₂] ' of the spent etching solution is oxidized (step 502 } to be [Cu(NH₃)J ^*t by the injected oxygen and ammonia gases in the second processing section, wherein the ammonia gas is the one extracted in the step of 500. Another portion of the spent solution, which is around 0. 6% to 0. 9% of the spent solution in the first section, is conveyed (step 600) to the electrolyzing device 70 to plate out the metal copper from the received spent etching solution. The electrolyzing device 70 includes an electrolyzing unit 70a and an intermediate tank 70b, wherein the electrolyzing unit 70a is used to plate out the metallic copper from the spent solution to reduce the copper ion concentration and the intermediate tank 70b stores the spent solution with a reduced copper ion concentration which flows from the electrolyzing unit 70a via a drain pipe 9. The gases escaped from the electrolyzing unit 70a is passed (step 601) to the second processing section to oxidizing the ion Cu^" of the spent etching solution in the second processing section to be the ion Cu" . Moreover, the gases from the intermediate tank 70b is also passed (step 601) to the second processing section . The spent solution wi th reduced concentra ion of copper in the intermediate tank 70b is conveyed (step 602) to the second processing section. In addition, the gases escaped from the etching device 10 is passed (step 700) to the second processing sec ion .

Referring to Fig.3, the first processing section further comprises a first processing unit 50a, a second processing unit having a first processing sub-unit 50b and a second processing sub-unit 50c, as well as a third processing unit 50d. The second processing section includes an oxidizing unit 50e and an oxidizing completing unit 50f . The spent etching solution is firstly conveyed to the first processing unit 50a via the pipe 100 and extraction of ammonia gas is carried out in the first processing unit 50a by such as an extraction pump in order to stabilize the copper complex [Cu (NH₃) ₂) ^* , wherein the spent etching solution in the first processing unit 50a generally includes ( NH₄ ) ₂ S0₄ , NH„C1 , ( NH₄ ) ₃P0₄ , CuS0₄ , CuCO_$ , NH₃ / NH..OH, etc. . The spent etching solution, after further extraction of the ammonia gas in the first process sub-unit 50b, is then conveyed to the second process sub-unit 50c to remove the ammonia gas again. Typically, the extraction of NH₃ from the spent solution in the first processing sub-unit 50b and second sub-unit 50c is performed by reducing the pressure to0.5-0.9atm Thereafter the spent solution flows to the third processing unit 50d from the second sub-unit 50c. With reduced concentration of ammonia gas, the spent solution in the third processing unit 50d has more capacity to absorb the excess gas which is conveyed by a gas connecting pipe 300 from the regenerating device 60, where the excess gas includes the ammonia and air. An injector can be used to make said excess gas dissolved in the spent solution of the third processing unit 50d. It is preferred that the pressure applied into the third processing unit 50dis inthe range from 1. Olatm to 1.05a m . The spent solution with absorbed said excess gas is conveyed to the first processing sub-unit 50b, in which the extraction of the ammonia gas is performed, and then conveyed to the second processing sub-unit 50c to remove the ammonia gas. After the ammonia gas extraction in the first and second processing sub-unit, the spent solution subsequently flows to the third processing unit 50d.For the purpose of extracting the ammonia gas in the spent etching solution and making the spent etching solution in the third processing unit 50d absorb more gases, especially the NH₃ produced in the regenerating device 60, a circuit is formed among the first processing sub-unit 50b, the second processing sub-unit 50c and the third processing unit 50d. It is preferred that the spent solution, before entering into the second processing section, flows in the circuit for several cycles to make the concentration of the ammonia gas to be around 2g/L through the extraction operation during flowing in the circuit, where the number of the cycles depends on the amount of the solution and so on.

It is desired that the spent etching solution can pass from the third processing unit 50d to oxidizing unit 50e under a pressure in the range from l.Olatm to 1.05atm. The oxidizing unit 50e further receives the solution conveyed from the intermediate tank 70b via a liquid connecting pipe 120, i.e. , the spent solution in the oxidizing unit 50e is the mixture of the solution from the intermediate tank 70b and the spent solution from the third processing unit 50d. The atmospheric oxygen from the etching device 10 is conveyed to the oxidizing unit 50e through a gas connecting pipe 210; and the pure oxygen and ammonia gas from the electrolyz ing unit 70a and the intermediate tank 70b are conveyed to the oxidizing unit 50e through a gas connecting pipe 220, and a gas connecting pipe 230, respectively. To ensure that the gases, especially che ammonia gas, are almost totally dissolved in the solution, an injector can be used to inject said gases into the oxidizing unit 50e, where the injector sucks out of the gases at a rate of 10-15m³/h. Moreover, the spent solution flows into the unit 50e at 9-18 m³/h and the pressure applied on the oxidizing unit 50e would be in the range from l.Olatm to 1.05atm.

In the oxidizing unit 50e, the following chemical reaction takes place to convert Cu^* into Cu";

[Cu(NH₃)₂]' + NH₃ + WH + 1/4 0_a -^Cu (NH₃) ,] " + 1/2Η_Γ:0 Therefore, taking as an example , in order to oxidize about 1 gram of [Cu(NH₃).]^* , about 0.17 gram of NH₃ , about 0.18 gram of NH₄',and about 0.08 gram of 0₂ are needed. That is, the [Cu (NH_j) ₂] ^* , NH_j , NH₄ ^* and 0₂ would be in the ratio about 100:17:18:8 for taking this chemical reaction. In another example of the present invention, the ammonia gas for this reaction can be obtained by separation from the gases escaped from the third processing unit 50d.

Then, the spent solution is conveyed from the unit 50e to the oxidizing completing unit 50f and the gas escaped from the unit 50e also flows to the unit 50f through a gas connecting pipe 260. Optionally, an air valve is set between the oxidizing unit 50e and the oxidizing completing unit 50f , which will open when the pressure in the unit 50e is above 1.05atm.

Moreover, the ammonia gases extracted from the first processing unit 50a, the first processing sub-unit 50b, and the second processing sub-unit 50c are also passed to the oxidizing completing unit 50f . In order for the solution in the oxidizing completing unit 50f to dissolve more ammonia gas, the spent solution is preferably injected to the oxidizing comple ing unit 5 Of under an inj ecting pressure be ween 1.05atm to 1.2atm. The quantity of ammonia gas in the solution of the oxidizing completing unit 50f is more than lOg/L. In the unit 50 , the oxidizing reaction is completed and the catalyst can be dosed to the etching solution as per the following chemical reaction :

2[Cu(NH₃)₂r + 2NH₃ + 2(ΝΗ₄Γ + / 0₂ — 2 [Cu ⁽ NH, ) ,]^rr

+ H-0

According to the present invention, around 0.6% to 0.9% of the volume of the spent etching solution in the first processing unit 50a is conveyed to the electrolyzing unit 70a. Since the extraction of ammonia gas has been done in the first processing section of the oxidizing device 50, the yield of the copper plating out in the electrolyzing unit 70a is improved and the following reaction is pushed toward a desired direction :

[Cu (NH,)„) ^** + 2e^" -eu + 4NH₃

2 [Cu (NH₃) ₂) ^* + 2e^" — 2Cu + 4NH₃ ®

20H —-1/2 0₂ + H₂0 + 2e^' ©

[CU (NH₃)J ⁺7 [Cu(NH₃)₂]^f + 20H^" Cu + 4 NH₃ + 1/20,®

Where the chemical reactions shown as equation (!) and (2) are the cathodic reaction, the chemical reactions shown as equation © is the anodic reaction, and the chemical reaction shown as equation ® is fostered if the dissolved NH₃ is reduced whereares the chemical reaction is fostered in a revere direction if the dissolved NH₃ or 0₂ is increased.

Turn to the flow diagram shown in Fig .5. The spent solution and the excess gases in the oxidizing completing unit 50 f are conveyed (step 503 ) to the regenerating device 60 through the liquid connecting pipe 130 and the gas connecting pipe 270, respectively. In the regenerating device 60a, the quantity of copper complex [Cu(NH₃)₄]^+* in the spent solution is increased (step 504) and the PH value is stabilized (step 504) approximately between 8.2-8.6.

Referring to Fig.3, the regenerating device 60 for making the spent etching solution ready for reemployment includes a first regenerating unit 60a and a second regenerating unit 60b, wherein the first unit 60a receives the passed spent solution as well as the gases from the oxidizing completing unit 50f , and the second unit 60b receives the spent solution which has been processed in the first unit 60a.

With the injected gases including ammonia gas and oxygen, the quantity of copper complex [Cu (NH₃) ,J " in the spent solution is increased upon the following reactions:

[Cu (NH₃) ₂] + → Cu' + 2NH₃;

Cu' + 2NH_j + 2NH, + l/20₂ → Cu^** + 4NH₃+ H₂0;

Cu^** + 4NH₃ - [Cu(NH₃)J"

It should be understood that in the reaction of ^""Cu^" + nNH₃ → [Cu (NH₃) _n] "^{T 11} , n is a natural number of one of 1,2,3,4 and 5.

Referring to Fig .5 , the NH₃ needed in the above reactions is obtained by means of separating the pure ammonia gas from the gases escaped from the third processing unit 50d by the gas process device.

Then the solution is conveyed from the first regenerating unit 60a to the second unit 60b to stabilize the copper complex [Cu (NH₃) ₄] and to make the PH value be stabilized between 8.2-8.6 according to the following reaction:

NH₃ + H₂0 ^ NH₄ ^* + OH^"

And the copper complex, formed with the ligand NH_j according to the following reaction, is stabilized through the gases escaped from the first unit 60a.

Cu(H,0)J " + nNH₃ < = > [Cu(NH_j)_n ^* + nH₂0

In the second regenerating unit 60b, It is preferred that an injector can be used to suck out of the gases which are not dissolved in the spent solution thereof and re-inject the sucked gases tothe spent solution soas to make more ammonia gas dissolved in the spent solution of the second unit 60b.

The excess gases, which is escaped from the second regenerating unit 60b, is passed (step 505) to the third processing sub-unit 50d to be absorbed by the solution in the chird processing sub-unit 50d. The solution with absorbed ammonia gas will flow in the circuit for such as 3 cycles, such that the ammonia gas is extracted.

Turn to Fig.5 again, the spent etching solution in the second regenerating unit 60b, which is ready for reemployment in the forgoing processes, is conveyed (step 506) to the spray unit of the etching device 10, serving as an etching solution. When the etching device 10 does not etch, the spent etching solution in the second regenerating unit 60b ready for the reemployment is conveyed (step 508) to first processing unit

20 50a .

Fig.6 shows the flow diagram of the gas process of the gases escaped from the third processing unit 50d . The fol lowing description will also refer to Fig.3.

The gas process device includes a condensator 170, a separating unit 180, a scrubber 190 and a neutralizer 20. The condensator 170 receives {step 800) the gases escaped from the third processing unit 50d, which includes the ammonia gas and the air which are not utilized in the second generating unit 60b_; through the gas connecting pipe 310. In the condensator 170, the ammonia is separated (step 802) from the gases by for example reducing the temperature to be below 10 ^CC, and the separated ammonia gas goes towards the top of the condensator 170 since its density is less than the other gases', whereas the other gases without separated ammonia go to the bottom of the condensator 170. The separated ammonia gas is passed (step 804) to the oxidizing completing unit 50f through a gas connecting line 340 so as to oxidize Cu^* to Cu", and the other gases in bottom of the condensator 170 flows (step 806) through a gas connecting pipe 350 to the scrubber 190 where the solution in the scrubber 190 comes from the first rinsing sub-unit 80a and the neutralizer 20. The spent solution in the first rinsing sub-unit 80a is the most polluted one for it is the first cascade to clean the etched circuit board; and the rinsing solution in the first rinsing unit 80a is conveyed to the scrubber 190 via a liquid connecting pipe 430 when the salt concentration therein reaches 50% of that of the spent etching solution in the etching device 10. In the scrubber 190, the following chemical reaction takes place:

[Cu (NHj)_n (NH₄) J ^*(m*2) + NH₃ - [Cu(NH₃)_n]" + mNH,^' H_j + H" — NH₄ ^*

Then the resulted solution in the scrubber 190 is supplied (step 808) to the oxidizing unit 50e via a liquid connecting pipe 440 to make up for the water lost by evaporating and to enrich the solution with the ion NH₄ ^* required for the oxidation reaction, whereas the exhausted gases escaped out of the solution in the scrubber 190 is passed (step 810) to the separating unit 180 through a gas connecting pipe 360. As an example, the gases escaped from the scrubber 190 can be injected into the separating unit 180 by a flow injector.

The separating unit 180 comprises a first separating sub-unit 180a, a second separating sub-unit 180b, and a third separating sub-unit 180c . The condensate in the condensator 170 , which comprises the water and the gases from the third processing unit 50d other than the extracted ammonia gas, is transferred (step 812) to the second separating sub-unit 180b through a connecting pipe 510 and will release the dissolved ammonia gas due to an aspiration which reduces the pressure of the sub-uni 180b. Then the released ammonia gas is injected {step 814) into the first regenerating part 60a through a gas connecting pipe 380. The condensate in the second separating sub-unit 180b is conveyed to the first separating sub-unit 180a via a pipe 520 in order to absorb the gas coming from the scrubber 190 via the pipe 360. It is preferred that a pump is installed in the separating unit 180 to make the condensate circulate between the second separating sub-unit 180b and the first sub-unit 180a with a pressure of 1.05-1.2atm, such that the solubili y of gases which comes from the scrubber 190 in the solution of the separating sub-unit 180a is increased.

After circulating between the second separating sub-unit 180b and the first sub-unit 180a for a certain number of cycles, where the number of cycles depends on the supplying rate of the condensate from condensator 170, the condensate, i.e. the solution in the second sub-unit 180b, is fed to the chird separating sub-unit 180c for a further ammonia gas extraction and then is passed to a water tank 400. The ammonia gas extracted by the extraction performed in the separating sub-unit 180b and 180c goes (step 816) to the first regenerating unit 60a through the gas pipe 380 to contribute to the chemical reaction taking place in the first regenerating unit 60a, and the excess gases which are not dissolved in the solution of the first sub-unit 180a escape from the first separating sub-unit 180a to (step 818) the neutralizer 20 through a gas pipe 370 for the final treatment before they go outside of the recovering system. It can be understood that an environment with low pressure should be formed in the second separating sub- uni t 180b and thi d sepa at ing sub- uni tl80asoas to e trac - more ammonia gas, and an environment with high pressure should be formed in the first separating sub-unit 180a to dissolve more gases from the scrubber 190.

In the neutralizer 20, there are chemical reactions between the minim amount of the ammonia gas and the solution, which contains 5-15% of sulfuric acid, as follows:

H₂S0_« + 2NH-, → (NH₄)2S0₄

NH₃ + H^* — NH

The solution in the scrubber 190 is conveyed (step 820) to the oxidizing unit 50e, thereby making up for the lost water in the oxidizing unit 50e and enriching the NH,' of the solution in the unit 50e. The injection of ammonia gas into the spenc etching solution will increase the difference between the chemical potentials of the oxidation pairs Cu++ /Cu+ and Cu+/Cu as indicated in f igure 4 , which supports the etching and improves the production efficiency as well as the production quality ([Cu (NHj) J '^* + Cu —2 [Cu (NH₃ ) ₂] ^* ) . The extraction of ammonia gas from the etching solution fosters the electrolysis process by increasing the due potential difference of the oxidation pairs Cu"/Cu' and CuVCu as indicated by figure 4.

Fig.7 shows the flow diagram of the procedure for the water process device . The following description will also refer to Fig.3.

The condensate from the third separating sub-unit 180c, is conveyed (step 700) to a first tank 400 through a liquid connecting pipe 530. And the solution, which is passed separately from any of the second rinsing sub-unit 80b and the third rinsing sub-unit 80c to a liquid pipe 450 if the salt concentration of the rinsing solution therein is above 1 gram per liter, is conveyed to (step 701) a second tank 410, wherein the rinsing solution flows from the second rinsing sub-unit 80b to the pipe 450 by a sub-pipe 450b and from the third rinsing sub-unit 80c to the pipe 450 by a sub-pipe 450c.

The solution in the second tank 410 then is passed (step 702) through a liquid pipe 460 to the osmosis unit 390 where pure water is obtained by the osmosis operation. The obtained pure water is conveyed (step 704) to a third tank 420 through a liquid pipe 470, and the water in the third tank 420 is continuously passed (step 706) through a liquid pipe 500 to the third rinsing sub-unit 80c. The remaining solution in the osmosis unit 390 is conveyed (step 708) to the first tank 400 through a liquid pipe 480 where the conveyed solution is mixed with the solution passed from the third separating sub-unit 180c. When the salt concentration in one of the fist rinsing sub-unit 80a, the second rinsing sub-unit 80b, the third rinsing sub-unit 80c exceeds the preset value suchaslg/L, the resulting mixture solution in the first tank 400 is fed (step 710) to the fist rinsing sub-unit 80a, the second rinsing sub-unit 80b, and the third rinsing sub-unit 80c through a liquid connecting pipe 490a, 490b and 490c, respectively, so as to adjust the concentration of salt in the rinsing solution. The rinsing solution in the third rinsing sub-unit 80c can flow to the second rinsing sub-unit 80b. Since the solution in the water process device can flow to and from the rinsing unit 80, the solution in the scrubber 190 is updated based on the liquid connecting pipe 430.

It can be seen that the etching device, the oxidizing device, the regenerating device , the electrolyzing device , the gas processing device and the water processing device form a closed recovering system, where the spent etching solution is converted to be the etching solution with the gases extracted or escaped from the spent etching solution. The spent etching solution, upon this recovering system and method, can be recovered up to almost 100%.

Claims

What is claimed is:

1. A system for recovering a spent etching solution, including: an etching device , used for an etching react ion , the etching reaction producing the spent etching solution; an oxidizing device, including: a first processing section connected to the etching device, used for receiving the spent etching solution passed from the etching device, the first processing section extracting ammonia gas from the spent etching solution; and a second processing section connected to the firs- processing section, used for oxidizing the copper ion in the spent solution passed from the first processing section; a regenerating device connected to the second processing section, used for increasing the concentration of the copper complex [ Cu ( NH₃ ) , ] ^*"* and adjusting the PH value of the spent etching solution which is passed from the second processing section, the spent etching solution with the increased concentration of the copper complex and the adj us ted PI! value being passed to the etching device to serve as an etching solution; and an electrolyzing device, including: an electrolyzing unit connected to the fist processing section, used for plating out the copper from the spent solution which is conveyed from the first processing section; an intermediate tank connected to the electrolyzing unit, receiving the spent solution with reduced cooper

concentration from the electrolyzing unit; wherein the ammonia gas extracted from the first processing section is passed to the second processing section, the gases escaped from the second processing section are passed to the regenerating device, and the gases escaped from the regenerating device are passed back to the first processing section,- and wherein a gases escaped from the etching device, the electrolyzing unit, and the intermediate tank are passed to the second processing section.

The system of claim 1, wherein the etching device includes a spray unit for spraying the etching solution, a solution tank for storing the spent etching solution, and a rinsing unit for cleaning an etched circuit board.

The system of claim 1 or 2, wherein the first processing section includes a first processing unit connected to the etching device, a second processing unit connected to the first processing unit, as well as a third processing unit connected to the second processing unit, such that the spent etching solution flows from the first processing unit to the third processing unit through the second processing unit ,· and the second processing section includes an oxidizing unit connected to the third processing unit and a oxidizing completing unit which is connected to the oxidizing unit, such that the spent etching solution is conveyed from the third processing unit to the oxidizing completing unit through the oxidizing unit.

The system of claim 3, wherein the second processing unit includes a first processing sub-unit and a second processing sub-unit, wherein a circuit is formed among the first processing sub-unit, the second processing sub-unit and the third processing unit.

5. The system of claim 4, wherein the spent etching solution flows in the circuit for three cycles before the spent etching solution is conveyed to the oxidizing unit.

6. The system of claim 4 or 5 , wherein ammonia gas is extracted from the first processing unit , the first processing sub-unit , and the second processing sub-unit , and the extrac ed ammonia gas is passed to the oxidizing completing unit.

7. The system of claim 6 , wherein gases escaped from the oxidiz ing unit are passed to the completing oxidizing unit.

8. The system of claim 6 , wherein gases escaped from the etching device, the electrolyzing unit, and the intermediate tank are passed to the oxidizing unit.

9. The system of claim 6 , wherein the regenerating unit includes a first regenerating unit for adjusting the PH value of the spent etching solution in the range from 8.2 to 8.6 and a second regenerating unit for increasing the concentration of the copper complex [Cu (NH₃) J "^* in the spent etching solution passed from the oxidizing completing unit.

10. The sys em of claim 9 , wherein gases escaped from he firs regenerating unit are passed to the second regenerating unit .

11. The system of claim 10, wherein an injector is used to suck out of the gases from the second regenerating unit and re-inject into the spent etching solution in the second regenerating unit.

12. The system of claim 9, wherein the second regenerating unit is connected to the first processing unit.

13. The system of claim 4, wherein 0.6% to 0.9% of the spent etching solution volume coming from the etching device is conveyed to the electrolyzing unit.

14. The system of claim 13, the spent solution in the intermediate tank is passed to the oxidizing unit.

15. The system of any one of claims 9-14, further including a gas processing device which extracts ammonia gas out of the gases escaped from the third processing unit and ransfers the extracted ammonia gas to the oxidizing completing unit.

16. The system of claim 15, wherein the gas processing device includes a condensator, a scrubber, and a separating unit, wherein : the condensator receives the gases escaped from the third processing unit and separates ammonia gas from said gases by means of condensation, and said ammonia gas is passed to the oxidizing completing unit; the scrubber receives the remaining gases in the condensator and scrubs these g ses by a solution in the scrubber, wherein part of the solution in the scrubber comes from the rinsing unit and the solution in the scrubber is passed to the oxidizing unit; the separating unit receives the condensate from the condensator, and receives gases passed from the scrubber as well as separates ammonia gas from said gases, and the separated ammonia gas is passed to the first regenerating unit.

17. The system of claim 16, wherein the separating unit includes a first separating sub-unit and a second separating sub-unit, the second separating sub-unit receiving the condensate conveyed from the condensator and releasing the ammonia gas contained in the condensate by means of a reduced pressure, the condensate then being conveyed to the first separating sub-unit from the oecond separating sub-unit, the first separating sub-unit receiving the gases f om the scrubber and the condensate therein absorbing the gases by means of a increased pressure, the condensate with the absorbed gases from the scrubber in the first separating sub-unit being conveyed back to the second separating sub-unit.

18. The system of claim 17, wherein the separating unit further 5 includes a third separating sub-unit which receives the

condensate conveyed from the second separating sub-unit and extracts the ammonia gas contained in the condensate.

19. The system of claim 15, wherein the gas processing device further includes a neutralizer which contains a neutralizing

10 solution for neutralizing the excess gases passed from the separating unit.

20. The system of claim 19, wherein the neutralizing solution is passed to the scrubber.

21. The system of any one of claims 16-20, further including I D a water process device to recover a rinsing solution of the rinsing unit.

22. The system of claim 21, wherein the rinsing unit further includes a first rinsing sub-unit, a second rinsing sub-unit, and a third rinsing sub-unit. 0 23. The system of claim 22, wherein the water process device includes a first tank, a second tank, a third tank and an osmosis unit, wherein: the first tank receives the solutions conveyed separately rom the separa ing unit and the osmosis unit , as well as supplies 5 the mixed solution to the first rinsing sub-unit, the second rinsing sub-unit, and the third rinsing sub-unit; the second tank receives a solution from the second and third rinsing sub-units and supplies it to the osmosis unit;

3, the osmosis unit processes the solution supplied from the second tank to obtain pure water to be conveyed to the third tank; and the third tank stores the pure water and supplies them to 5 the third rinsing unit when the salt concentration in the third rinsing unit is more than a preset value.

24. The system of claim 23, wherein the first tank receives the solution conveyed from the third separating sub-unit and the osmosis unit.

'. C

25. A method for recovering a spent etching solution , including: a) extracting an ammonia gas from the spent etching solution which is contained in a first processing section of an oxidizing device ; b) conveying the spent etching solution obtained in step lb a to a second processing section of the oxidizing device; c) oxidizing the copper ion Cu^* in the spent solution into Cu^*' with the ammonia gas extracted in step a according to the reaction [Cu(NH₃)₂]^* + NH₃ + NH. ^* + 1/4 0₂ —{ Cu ( H₃ )„ ] " + l/2H0 in the second processing section; 0 d) conveying the spent etching solution which is oxidized in step c to a regenerating device to increase the concentration of the copper complex [Cu(NH₃)J^*+ according to the following chemical reaction,

[CU (NH-,) ₂] ^* -* CU^T + 2NH₃;

5 Cu^T + 2NH₃ + 2NH„ + l/20₂ → Cu" + 4NH₃+H₂0;

and stabilize [Cu(NH,)J^** as well as the PH value of the spent etching solution upon the following chemical reaction, NH₃ + H₂0 <→ NH„⁺ -i- OH^"

; and e) conveying the spent etching solution obtained in step d to an etching device to serve as an etching solution.

26. The method of claim 25 , wherein the step of b further includes: b conveying 99.1% to 99.4% of the volume of the spent etching solution in the first processing section to the second processing section of an oxidizing device; and conveying the remaining spent etching solution to an electrolyz ing device where the copper is plated out. G

27. The method of claim 26, the method further including: passing gases produced during plating out the copper to the second processing section of the oxidizing device; passing gases extracted from the spent etching solucion in che etching device to the second processing section of the5 oxidizing device; and conveying the spent solution in the electrolyzing device after the operation of plating out the copper to the second processing section of the oxidizing device.

28. The method of any one of the claims 25-27, wherein the step0 a further includes extracting the ammonia gas from the spent etching solution in a first processing unit and a second processing unit of the oxidizing device; then in a third processing unit, absorbs gases passed from the regenerating device . b

29. The method of claim 28 , wherein gases escaped from the third processing unit is conveyed to a gas process device to obtain ammonia gas from the gases.

30. The method of claim 29, wherein the gases escaped from the third processing unit is conveyed to a condensator to separate the ammonia gas from said gases by means of condensation, and the separated ammonia gas is conveyed to an oxidizing completing

5 unit of the second processing section of the oxidizing

31. The method of claim 30, wherein the remaining gases after condensation is conveyed to a scrubber to be scrubbed, the solution contained in the scrubber comes from a rinsing unit which is used to clean the etched circuit board. C

32. The method of claim 31, wherein the solution in the scrubber in conveyed to the second processing section of the oxidizing device to recover spent solution from the rinsing unit.

33. The method of claim 30, wherein the gases escaped from the scrubber are conveyed to a separating unit to separate the ammonia5 gas from said gases escaped from the scrubber, and the separated ammonia gas is conveyed to the regenerating device.

34. The method of claim 33 , wherein the solution in the separating unit is conveyed from the condensator.

35. The method of claim 33, wherein the gas escaped from the0 separating unit is passed to a neutralizer to neutralize a minitr. amount of the ammonia gas .

36. The method of claim 33 , wherein the solution in the separating unit is conveyed to a first tank of a water process device.

37. The method of claim 34, wherein a rinsing solution of a5 first rinsing sub-unit of the rinsing unit is conveyed to the scrubber, the solution of a second rinsing sub-unit and the solution of a third rinsing sub-unit is conveyed to the second tank .

38. The method of claim 37, wherein the solution in the second tank is conveyed to an osmosis unit to obtain pure water.

39. The method of claim 38, wherein the pure water is stored in a third tank, and the water in the third tank is conveyed to the third rinsing unit.

40. The method of any one of claims 27-39, wherein the spent etching solution with increased concentration of [Cu(NH₃)₄]" and stabilized PH value in the regenerating device is conveyed to the first processing section of the oxidizing device.