CN85106153A

CN85106153A - Method at etching printed circuit plate

Info

Publication number: CN85106153A
Application number: CN 85106153
Authority: CN
Inventors: 维利·拜尔; 雷纳·哈斯
Original assignee: Hans Hollmuller Maschinenbau & Co (de) Kappstr 69 7033 Herrenberg-Gultste GmbH
Current assignee: Hans Hollmuller Maschinenbau & Co (de) Kappstr 69 7033 Herrenberg-Gultste GmbH; Hollmuller Hans Maschinenbau GmbH and Co
Priority date: 1985-08-15
Filing date: 1985-08-15
Publication date: 1987-03-04

Abstract

Set forth a kind of technical process with copper film on the sodium sulphate ammonia solution Etched Printed Circuit plate, also added bromo-containing substance in the used etching solution and make catalyst, especially NHBr or CHCHBrCOBr are to improve etching speed.From this etching solution, might be on the high-quality steel electrode, pliable and tough copper adhesion layer is separated out in electrolysis, and will strip down on its self-electrode easily.

Description

Method at etching printed circuit plate

The present invention relates to a kind of technology, in etching printed circuit plate, electrolytic recovery copper from etching solution.

Nowadays industrial main method as the Etched Printed Circuit plate, its etching solution has used [Cu(NH ₃) ₄] Cl ₂And NH ₃Fortified aqueous.Cupric in the solution, the metallic copper thin layer copper exposure portion on the printed circuit board (PCB) is oxidized to monovalence copper: in oxidizing process, cupric itself also changes into monovalence.Monovalence copper in the salting liquid then is subjected to oxygen effect in the air, is oxidized to cupric again, can use for etching again then.

After the long-term use of etching solution, copper content wherein must lower again.Because the electrolysis segregation process can discharge Cl simultaneously ₂, can not reduce copper content with it.Therefore, can adopt liquid-liquid extraction method, above β-two bronze medal of unnecessary copper fixation in being dissolved in kerosene, this compound itself is water insoluble, subsequently, with sulfuric acid copper is decomposed out again, obtains copper sulphate thus.The latter can generate metallic copper by electrolysis by usual way then.

The above-mentioned method of handling etching solution again is too complicated, can only carry out in the chemical enterprise for this purposes preparation.Printed circuit board (PCB) manufacturer has to sending this business processes back to the etching solution of crossing.

No doubt, also may adopt [Cu(NH ₃) ₄] SO ₄Fortified aqueous come the Etched Printed Circuit plate.The copper that dissolves in addition in etching can be easy to from such solution electrolysis and separate out.But if adopt such etching solution, its etching period is than using CuCl ₂/ NH ₃Solution is much longer.

In order to shorten use [Cu(NH ₃) ₄] SO ₄The needed etching period of solution among the former application for patent P3305319.7, was once mentioned at [Cu(NH ₃) ₄] SO ₄Added a kind of catalyst in the concentrated solution, i.e. vanadium or vfanadium compound.But, from containing [the Cu(NH of ferrous vanadic salts (Vanadiferrous) ₃) ₄] SO ₄The copper of separating out in the etching solution does not have adhesiveness, easily scaling, and be difficult to take away on the electrode by segregate copper.In addition, the copper layer thickness of separating out on electrode increases, and electrolytic efficiency also descends thereupon.

Purpose of the present invention provides a kind of method at etching printed circuit plate.It can make [Cu(NH with electrolytic method simultaneously in etching ₃) ₄] SO ₄Etching solution holomorphosis; And in the process of electrolysis recovery copper, can obtain adhering copper layer.At this moment, the etching process of printed circuit board (PCB) is still quickened by catalysis.

Be resolved according to this difficult problem of the present invention.

According to method of the present invention, adopt bromo-containing substance to make catalyst, this compound is not to exist with the cation state in etching solution, it does not emanate out with copper in the process of electrolytic recovery copper yet.From containing [the Cu(NH of ferrous vanadic salts (Vanadiferrous) ₃) ₄] SO ₄The copper of separating out in the etching solution, bad mechanical strength is estimated its reason, may be owing to be mixed with vanadium in the copper of separating out.According to the inventive method, the bromo-containing substance that is used as catalyst does not form cation, therefore, can not emanate out with copper.Thereby, on electrode, generate pure pliable and tough copper layer.Brominated catalytic specie also is worthwhile with regard to cost.

Hereinafter will give unique diagram, the present invention will be described in more detail.Illustrated system can be used to continuous Etched Printed Circuit plate, and with electrolysis from the etching solution copper of emanating, solution is constantly regenerated.

Among the figure, elongated chest 10 is drawn as cross section.The storage tank 12 of etching solution is made in chest 10 belows.The latter is joined with the vacuum end of pump 16 by pipeline 14.The exhaust end of pump joins with lower end shower 18 and upper end shower 20.

Between

shower

18 and 20, an endless conveyor belt with holes 22 is arranged, it, transmits by chest 10 along perpendicular to the picture direction constantly printed circuit board (PCB) 24.Printed circuit board surface has at least one to be covered with banded copper film, scribbles photonasty diaphragm (photoresist) on it; some place is through exposure and development treatment subsequently on the diaphragm; be removed, have only those places of forming circuit plate later on like this on the copper film, still scribble diaphragm.Then coming out in other position of copper film, and suffers the corrosion by the etching solution 26 of

shower

18,20 ejections.

Fresh etching solution component contains 1.227 mol [Cu(NH ₃) ₄] SO ₄, 0.01～0.6 mol free state NH ₃, and 0.606 mol (NH ₄) ₂SO ₄The etching solution temperature is 323～325K(50～52 ℃).Also have bromo-containing substance to make catalyst in addition in the etching solution, to improve etching speed.To this, the back will be described in more detail.

In less than one minute time, etching solution can be with the whole strippings of copper of unprotect membranous part position on the 35 micron thickness copper films.According to equation Cu+Cu ²⁺-2Cu, beginning generates monovalence copper earlier.It is subjected to dioxygen oxidation in the air again, and like this, whole etching operation reactional equation is as follows:

Since in the etching operation in the solution concentration of copper, must from solution, remove an amount of copper for etching solution regeneration along with the time raises.

For this purpose, chest 10 is connected with electrolysis tank 18 by another root pipeline 27, and electrolysis tank has negative electrode 30 and anode 32, their link to each other with power supply (not expressing on the figure).Because the middle direction of above-mentioned equation (1) in reactive tank 28, takes place and finishes opposite reaction in the decomposition voltage that adds, like this, free ammonia and (NH in the etching solution ₄) ₂SO ₄Content increases.The brominated catalytic material that has in addition in the etching solution is not influenced by electrolysis, and it through another pump 34 and pipeline 36, is sent back to chest 10 with etching solution together.

Through electrolysis, the copper in the solution is separated out postprecipitation on negative electrode 30, constitutes adhesiveness and pliable and tough copper layer, and it strips down from the negative electrode of being made by the high-quality steel with the method for machinery easily.

Hereinafter will list some brominated catalytic materials that can improve etching speed for example, and thus obtained etching speed.

The etching solution of each test usefulness has basic composition mentioned above and the temperature of indicating.

Example 1: adopt KBr to make brominated catalytic specie.

In the record of following table, listed the concentration of catalytic specie, the pH value of etching solution when 323～325K, and finish 35 microns needed times of copper film of etching.

Can find that owing to add catalyst, etching period can shorten half.

Catalyst addition (grams per liter) pH value etching period (second)

0????8.79????98

0.5????8.79????68

1.0????8.79????63

2.0????8.79????57

2.0????9.25????60

2.0????9.1????58

3.0????9.25????50

3.0????9.1????47

4.0????9.2????46

4.0????8.8????44

6.0????8.9????46

Example 2: adopt NH ₄Br makes catalytic specie

Following table has been listed the record of the etching speed that obtains once more.

Catalyst addition (grams per liter) pH value etching period (second)

0????8.9????96

0.1????8.9????68

1.0????8.9????53

3.0????8.9????50

4.0????8.9????49

6.0????8.9????49

8.0????8.9????49

Example 3: adopt the superpurity bromine to make catalytic specie

Because reaction is too fierce, pure bromine can only be dissolved in the chloroform, uses (maximum acceptable concentration MAC value=0.1PPM) can obtain following etching speed with very rare form.

Catalyst addition (grams per liter) pH value etching period (second)

0????8.84????112

0????9.04????107

0.1????9.0????62

0.5????9.03????55

0.8????9.03????43

1.45????9.03????40

2.0????9.03????40

Example 4: adopt N-cetyl-N, N, N-trimethylammonium bromide (C ₁₉H ₄₂BrN) make catalytic specie.

If use this catalytic specie, also should take measures to reduce the foaming of etching solution in spray.The etching result that obtains is as follows:

Catalyst addition (grams per liter) pH value etching period (second)

0????9.0????103

0.1????9.0????90

0.5????9.0????62

1.0????9.0????62

2.0????9.0????72

4.0????9.0????78

Example 5: adopt bromo acetyl group bromide (C ₂H ₂Br ₂O) make catalytic specie.

If when adopting this easy volatilization and poisonous catalytic specie, must suitable in addition safeguard measure.The etching result that obtains is as follows:

Catalyst addition (grams per liter) pH value etching period (second)

0????8.55????98

0.9????8.55????49

1.8????8.55????47

2.0????8.55????46

3.0????8.9????45

5.0????8.9????48

7.0????8.9????50

Example 6: adopt 2-bromo propionyl bromide (CH ₃CHBrCOBr) make catalytic specie.

The etching result that obtains is as follows:

Catalyst addition (grams per liter) pH value etching period (second)

0????8.27????105

1.0????8.27????51

2.0????8.10????49

2.0????8.7????48

3.0????8.94????47

3.0????9.48????44

4.0????9.4????40

4.0????9.3????37

4.0????9.35????39

5.0????9.35????38

7.0????9.35????39

10.0????9.35????38

Should be pointed out that from above example originally etching speed increases with the catalyst addition and accelerate, but the active bromine addition surpasses about 4 grams per liters, promptly reaches saturated; Continuing increases catalyst concn, and etching speed is not had obvious raising again.

From above example, obviously, etching speed is also relevant with the pH value of etching solution.Here listed another example of representing this influence.The Cu layer that it relates to 35 micron thickness is in 325～326K(52～53 ℃) time etching period, all the other components of used etching solution are 1.369 mol [Cu(NH ₃) ₄] SO ₄, and 0.606 mol (NH ₄) ₂SO ₄(this numerical value is along with generating [Cu(NH in the etching ₃) ₄] SO ₄And descend).Used etching solution contains 3.3 gram Br respectively ^-/ liter.

PH value free state NH ₃(mol) etching period (second)

8.75????0.01????53

8.8????0.061????51

8.95????0.151????50

9.05????0.271????51

9.3????0.541????53

9.3????0.641????50

9.45????0.871????59

9.75????1.621????68

In the catalytic specie example listed above, recommend to make use-case 2 and example 6, this is because each used catalytic specie is handled easily, does not also have undesirable pair of reaction, and can make etching obtain gratifying raising.

Claims

1, at etching printed circuit plate, the technology of electrolytic recovery copper from etching solution is removed [Cu (NH in the etching solution simultaneously ₃) ₄] SO ₄, NH ₃(NH ₄) ₂SO ₄In addition, also contain a kind of catalyst, to improve etching speed, etching solution contact print circuit board, the copper that etching is got off is separated out in etching solution with electrolysis, and Zai Sheng salting liquid returns in this technical process and uses thus, it is characterized in that etching solution contains the bromine material and makes catalyst.

2, according to the technology of claim 1, the active bromide concentration that it is characterized in that catalytic action is 0.1～8 grams per liter.

3, according to the technology of claim 2, the active bromide concentration that it is characterized in that catalytic action is 1～4 grams per liter.

4, according to the technology of claim 1, it is characterized in that containing material is a kind of bromide.

5,, it is characterized in that this bromide is NH according to the technology of claim 4 ₄Br or CH ₃CHBrCOBr.

6, according to the technology of claim 1, it is characterized in that the etching solution operating temperature is 318～328(45～55 ℃).

7, according to the technology of claim 1, it is characterized in that the pH value of etching solution operation is 8.2～9.5, pH value is to be 327K(54 ℃ at solution temperature) time measures.

8, according to the technology of claim 1, the concentration that it is characterized in that free ammonia is between 0.01 to 1.0 mol.

9,, it is characterized in that Cu concentration is 70～120 grams per liters in the etching solution according to any one technology in the claim 1 to 8.