Copper etching liquid with high etching factor and preparation method and application thereof

Abstract

The invention provides a copper etching solution with a high etching factor as well as a preparation method and application of the copper etching solution. The copper etching solution with the high etching factor comprises the following components in parts by weight: 0.48-3 parts of a corrosion inhibitor; 1-10 parts of an oxidizing agent; 10 to 20 parts of inorganic acid; 0.1-1 part of an organic solvent; 60 to 80 parts of ultrapure water; the corrosion inhibitor is a mixture of a benzothiazole corrosion inhibitor and an aminoimidazole corrosion inhibitor. The copper etching liquid with the high etching factor has the high etching factor, copper can be rapidly and efficiently removed, the side wall etching time is shortened, and therefore the product yield is increased. And the method has very good application prospect and large-scale industrial popularization potential in the field of circuit board packaging.

Description

TECHNICAL FIELD

[0001] The present application relates to etching liquid technology, in particular to a copper etching liquid with high etching factor and its preparation method and application. BACKGROUND

[0002] The subtractive process is a traditional process in the field of integrated circuits and electronic packaging, the core of which is to remove the excess material on the substrate through physical or chemical methods (such as etching, laser cutting, etc.) to form the required circuit or structure. In the processing of chip on film (COF), the subtractive process is mainly applied to the line production of flexible substrates (such as polyimide film), and the specific process includes steps such as copper cladding, photolithography, and etching. Early electronic packaging technologies (such as COG and TCP) rely on the subtractive process because of its mature process and high standardization of equipment. For example, in the packaging of panel driving chips, fine lines are formed by etching copper-clad foil, but due to the limitation of etching factor, the line width precision is usually difficult to break through 15μm. Moreover, during the etching process, as the etching time increases, the etching factor of the line will decrease. At the same time, the acid value of the acidic etching liquid is generally high, which will also have a great impact on the etching factor. Fine lines with low etching factor are prone to copper residue at the bottom of the line and result in a decrease in product yield.

[0003] Therefore, how to provide a copper etching liquid with a higher etching factor is a problem to be solved by the present application. SUMMARY

[0004] The purpose of the present application is to solve the problem of low product yield caused by small etching factor of traditional etching liquid and serious side etching, and to provide a copper etching liquid with high etching factor. The etching liquid has a higher etching factor and can quickly and efficiently remove copper, reducing the side wall etching time and thus improving the product yield.

[0005] It should be noted that in the present application, unless otherwise specified, the specific meaning of "including" involved in the composition limitation and description includes both open-ended "including", "containing" and the like, and closed "consisting of", "consisting of" and the like.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is: a copper etching liquid with high etching factor, comprising the following components in a weight ratio:

[0007]

[0008] The corrosion inhibitor is a mixture of benzothiazole corrosion inhibitor and amino imidazole corrosion inhibitor.

[0009] Further, the mass ratio of the benzothiazole corrosion inhibitor and the amino imidazole corrosion inhibitor is 1:15-100.

[0010] Further, the preferred mass ratio of the benzothiazole corrosion inhibitor and the amino imidazole corrosion inhibitor is 1:50.

[0011] Further, the benzothiazole corrosion inhibitor is one or more of 3-methyl-2(3H)-benzothiazolthione, 2(3H)-benzothiazolthione, 6-chloro-2-mercaptobenzothiazole, 5-bromo-2-mercaptobenzothiazole, and 2-mercapto-6-hydroxybenzothiazole.

[0012] Further, the benzothiazole corrosion inhibitor is preferably 6-chloro-2-mercaptobenzothiazole.

[0013] Further, the amino imidazole corrosion inhibitor is one or more of N-methyl-1H-imidazole-2-amine hydrochloride, 2-amino-1-methylimidazole, and 1-methyl-1H-imidazole-2-amine monohydrochloride.

[0014] Further, the amino imidazole corrosion inhibitor is preferably N-methyl-1H-imidazole-2-amine hydrochloride.

[0015] The present application adopts a mixture of benzothiazole corrosion inhibitors and amino imidazole corrosion inhibitors as corrosion inhibitors, and the synergistic corrosion inhibition mechanism is as follows:

[0016] Complementary adsorption sites: Benzothiazole corrosion inhibitors have strong coordination ability and can directly bind to the active sites on the copper surface to form a chemisorbed layer, preferentially covering the high-activity areas of copper. Amino imidazole corrosion inhibitors: can bind to the metal surface while forming a hydrophobic layer, hindering the penetration of corrosive media.

[0017] Synergistic effect: Benzothiazole corrosion inhibitors can fill the gaps between imidazole molecules adsorbed, forming a denser composite film with a larger coverage area, reducing the risk of localized corrosion.

[0018] Optimization of film structure: Amino imidazole corrosion inhibitors extend upwards through hydrophobic interactions to form a physical barrier layer; sulfhydryl molecules enhance the binding strength of the film to the copper matrix through chelation, improving the stability and durability of the film. The synergistic adsorption of the polar head of the imidazole ring and the sulfhydryl group can reduce the total energy of the system and improve the adsorption energy.

[0019] Synergistic barrier to corrosive media: The hydrophobic layer of amino imidazole corrosion inhibitors can hinder the penetration of water molecules and Cl-, while sulfhydryl groups inhibit the reduction reaction of H + through chemical adsorption, both of which synergistically reduce the cathode and anode reaction rates.

[0020] Further, the corrosion inhibitor is 0.48-1.5 parts.

[0021] Further, the oxidizing agent is phenethylamine sulfate and / or a nitro compound.

[0022] Further, the nitro compound is one or more of 2,2-dimethyl-3-(nitrooxy)propionic acid, 6-nitrohexanoic acid, and urea nitrate.

[0023] Furthermore, the oxidant is preferably phenylethylamine sulfuric acid and a nitro compound.

[0024] Furthermore, the mass ratio of phenylethylamine sulfuric acid to the nitro compound is 0.5-4:1.

[0025] Furthermore, the preferred mass ratio of the phenylethylamine sulfuric acid and the nitro compound is 1:1.

[0026] Furthermore, the oxidant is more preferably phenylethylamine sulfuric acid and 6-nitrohexanoic acid.

[0027] Furthermore, the mass ratio of phenylethylamine sulfuric acid to 6-nitrohexanoic acid is 0.5-4:1.

[0028] Furthermore, the preferred mass ratio of phenylethylamine sulfuric acid to 6-nitrohexanoic acid is 1:1.

[0029] The present invention utilizes the synergistic effect of phenylethylamine sulfuric acid and nitro compounds to etch copper.

[0030] The coordination effect of phenethylamine sulfuric acid is as follows:

[0031] Phenethylamine sulfuric acid dissociates in solution to release phenethylamine ions (C8H2O). 11 N + ), phenylethylamine ions can react with Cu 2+ Formation of stable complexes ([Cu(C8H) 11 N) n ] 2+ ), reducing the free Cu in the solution 2+ Concentration promotes the etching reaction in the forward direction and avoids the formation of a passivation layer; both factors work together to improve the etching rate and uniformity.

[0032] The oxidation of nitro compounds is as follows:

[0033] Nitro compounds, acting as strong oxidizing agents, can oxidize metallic copper (Cu) under acidic conditions. 0 ) oxidized to Cu 2+ :

[0034] 3Cu + 2NO3 - +8H + →3Cu 2+ +4H₂O + 2NO↑

[0035] The NO released in the reaction may be further oxidized to nitric acid, maintaining the oxidizing environment.

[0036] Further, the oxidizing agent is 4-10 parts.

[0037] Further, the inorganic acid is one or more of nitric acid, hydrofluoric acid, sulfuric acid and boric acid.

[0038] Further, the inorganic acid is preferably nitric acid.

[0039] Further, the inorganic acid is 15-20 parts.

[0040] Further, the organic solvent is one or more of dimethyl sulfoxide, ethylene glycol, isopropyl alcohol, N,N-dimethyl acrylamide and N,N-dimethyl formamide.

[0041] Further, the organic solvent is preferably N,N-dimethyl formamide.

[0042] Further, the organic solvent is 0.3-0.6 parts.

[0043] Further, the ultrapure water is 65-70 parts.

[0044] Further, the ultrapure water is deionized water with a resistance of at least 18MΩ.

[0045] Further, the etching factor of the high etching factor copper etching solution is ≥8.

[0046] Another object of the present application also discloses a preparation method of a high etching factor copper etching solution, comprising the following steps:

[0047] S1, respectively, the amount of each component is weighed;

[0048] S2, under stirring, add the oxidizing agent, inorganic acid, corrosion inhibitor and organic solvent to the ultrapure water, stir until completely dissolved, to obtain the high etching factor copper etching solution.

[0049] Another object of the present application also discloses the application of a high etching factor copper etching solution in the field of packaging circuit board etching.

[0050] Further, the steps of etching the packaging circuit board by using the high etching factor copper etching solution are as follows:

[0051] Step 1, at 35-40℃, the high etching factor copper etching solution is sprayed on the surface of the packaging circuit board, and the etching time is 20-60s;

[0052] Step 2, the etched packaging circuit board is sequentially washed by ultrapure water spraying, pickling, ultrapure water spraying, and drying, to complete the etching of the packaging circuit board.

[0053] Further, the spraying pressure in step 1 is 0.1-0.3 MPa.

[0054] Further, the ultrapure water spraying flushing time in step 2 is 5-20 s.

[0055] Further, the acid pickling in step 2 is carried out by using hydrochloric acid.

[0056] Further, the acid pickling time in step 2 is 5-20 s.

[0057] Further, the acid pickling time in step 2 is preferably 10 s.

[0058] Further, the drying temperature in step 2 is 20-150℃, and the drying treatment time is 40-100 s.

[0059] Further, the drying temperature in step 2 is preferably 80℃, and the drying treatment time is preferably 60 s.

[0060] Further, the ultrapure water in step 2 is deionized water with a resistance of at least 18 MΩ.

[0061] The copper etching liquid with high etching factor, the preparation method and application thereof have the following advantages compared with the prior art:

[0062] 1) The copper etching liquid with high etching factor is an acidic etching liquid, the etching factor of which is large, the etching rate is greatly improved, the etching time is obviously short, thereby reducing the side wall etching time and reducing the side etching phenomenon.

[0063] 2) In the copper etching liquid with high etching factor, the synergistic effect of benzothiazole corrosion inhibitor and amino imidazole corrosion inhibitor significantly improves the etching performance. The benzothiazole corrosion inhibitor can be closely adsorbed on the metal surface to reduce the etching rate, and the amino imidazole corrosion inhibitor can be uniformly adsorbed on the metal side wall, so that the etching behavior is close to anisotropy, the difference between the upper and lower sections of the etched circuit is small, and the etching factor is further improved.

[0064] 3) In the copper etching liquid with high etching factor, an organic solvent is introduced, which increases the surface tension and does not participate in the etching reaction, promotes the etching liquid to spread more uniformly on the surface of the packaged circuit board, and ensures the uniformity of the etching process.

[0065] 4) The oxidizing agent in the copper etching liquid with high etching factor is phenethylamine sulfate and / or nitro compound, which can improve the etching rate. Taking phenethylamine sulfate and nitro compound as examples, phenethylamine sulfate dissociates phenethylamine ion in the solution, and the phenethylamine ion can form a stable complex with Cu 2+ , such as [Cu(C8H 11 N) n ]2+ ), reduce the free Cu 2+ concentration in the solution, promote the above etching reaction to proceed in a positive direction, avoid the formation of a passivation layer, and collectively improve the etching rate and uniformity. As a strong oxidizing agent, the nitro compound oxidizes metallic copper (Cu 0 ) to Cu 2+ : The released NO in the reaction can be further oxidized to nitric acid, maintaining an oxidizing environment.

[0066] Therefore, the high-etch-factor copper etching solution of the present application has very good application prospects and large-scale industrialization potential in the field of packaging circuit boards. BRIEF DESCRIPTION OF DRAWINGS

[0067] Figure 1 is an OM image of the etching after using the etching solution of Comparative Example 2, magnified 2380 times;

[0068] Figure 2 is an OM image of the etching after using the high-etch-factor etching solution of Example 1, magnified 2380 times. EMBODIMENTS

[0069] The present application will be further described below in conjunction with examples. The description of the technical features described below is based on representative embodiments, specific examples of the present application, but the present application is not limited to these embodiments, specific examples. It should be noted that:

[0070] Unless otherwise specified, the units used in the specification are international standard units, and the values and value ranges appearing in the present application should be understood to include systematic errors that are unavoidable in industrial production.

[0071] In the specification, the value range indicated by "value A to value B" means a range including the end point values A and B.

[0072] In the specification, the value range indicated by "above" or "below" means a value range including the number.

[0073] In the specification, the meaning indicated by "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

[0074] In the specification, "optional" or "optionally" means that the use or non-use of certain substances, components, execution steps, applied conditions, etc.

[0075] In the specification, when "room temperature" or "room temperature" is used, the temperature can be 15-25°C.

[0076] In the specification, the reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained by purchase on the market.

[0077] Examples 1-12

[0078] Examples 1-12 disclose a plurality of high etching factor copper etching liquids, which contain components and weight ratios as shown in Table 1, and the preparation method is as follows

[0079] Step 1: weigh each component according to the respective amount;

[0080] Step 2: first add ultrapure water, and then add oxidizing agent, inorganic acid, corrosion inhibitor and organic solvent in sequence while stirring until completely dissolved, to obtain the high etching factor copper etching liquid.

[0081] Table 1 Components and ratios of high etching factor copper etching liquid of Examples 1-12

[0082]

[0083]

[0084] Comparative Examples 1-3

[0085] Comparative Examples disclose a plurality of copper etching liquids, which contain components and weight ratios as shown in Table 2, and the preparation method is the same as Example 1.

[0086] Table 2 Components and ratios of copper etching liquid of Comparative Examples 1-3

[0087]

[0088]

[0089] The use method of the high etching factor copper etching liquid disclosed by the present application comprises the following steps:

[0090] Step 1, at 35-40℃, the high etching factor copper etching liquid is sprayed onto the surface of the packaging circuit board, the spraying pressure is 0.1-0.3MPa, and the etching time is 20-60s;

[0091] Step 2, the etched packaging circuit board is sequentially washed by ultrapure water spraying for 5-20s, hydrochloric acid pickling for 5-20s, ultrapure water spraying for 5-20s, and drying at 20-150℃ for 40-100s, to complete the etching of the packaging circuit board.

[0092] The high etching factor copper etching liquid of Examples 1-12 and the copper etching liquid of Comparative Examples 1-3 are tested respectively, and the test method and test results are as follows:

[0093] The test method of performance 1 etching effect is:

[0094] Step 1: The copper etching solution for packaging circuit substrate was used to etch the sample at 40℃ by using a spraying machine, the etching time was 40s, and the spraying pressure was 0.2MPa;

[0095] Step 2: After etching, the sample was washed by spraying ultrapure water for 20s;

[0096] Step 3: Acid washing was performed, and the sample was washed by spraying hydrochloric acid with a mass concentration of 19% at a temperature of 39℃ for 10s;

[0097] Step 4: After acid washing, the sample was washed by spraying ultrapure water again for 20s;

[0098] Step 5: After washing, the sample was dried at a temperature of 80℃ for 60s.

[0099] The etching depth and the upper and lower line width of the material after copper etching were analyzed by OM, and the etching factor was calculated.

[0100] The etching factor = the ratio of 2 times the etching depth to the difference between the upper and lower line width.

[0101] The ultrapure water used in steps 1 and 2 was deionized water with a resistance of at least 18MΩ.

[0102] The test method for performance 2 etching rate was as follows:

[0103] The thickness was determined by five-point testing by using a thickness gauge, and the mass of the raw material was tested, and after the copper etching was completed, the mass was measured again, and the mass after etching was divided by the mass before etching, and then multiplied by the thickness before etching, and the resulting number was divided by the time, and the test results are shown in Table 3.

[0104] Table 3 test data

[0105] Etch factor Etch rate pm / min Example 1 16.8 8.9 Example 2 13.5 7.8 Example 3 12.7 8.2 Example 4 15.8 7.5 Example 5 15.2 6.8 Example 6 14.6 7.2 Example 7 15.3 6.5 Example 8 14.3 6.0 Example 9 13.9 6.1 Example 10 11.5 7.1 Example 11 7.2 2.4 Example 12 6.8 2.8 Comparative Example 1 7.5 4.0 Comparative Example 2 3.7 3.8 Comparative Example 3 4.8 3.2

[0106] Based on Table 3, it can be seen that the etching factor of the copper etching solution with a high etching factor according to the present application and examples 1-10 is greater than or equal to 10, and the etching rate is 6-9μm / min; while examples 11 and 12, due to the difference in corrosion inhibitor, the etching factor decreases, and the etching rate decreases; the etching factor of comparative examples 1-3 is less than or equal to 8, and the etching rate is 2-4μm / min. After etching with the copper etching solution with a high etching factor according to the present application, no product is generated on the substrate. That is, compared with the copper etching solution of the comparative example, the etching solution with a high etching factor according to the present application has a high etching factor and can quickly remove copper.

[0107] Figure 1 is an OM image of the sample etched by the etching solution with a high etching factor according to comparative example 2, magnified 2380 times; Figure 2is an OM image of Example 1 etching solution after magnification of 2380 times. From Figure 1 It can be seen that the upper and lower line width gap is large, and the etching factor of the etching solution of Comparative Example 2 is small; from Figure 2 It can be seen that the upper and lower line width gap is small, and the etching factor of the etching solution of Example 1 with high etching factor is large.

[0108] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A copper etching solution with a high etching factor, characterized in that, The components include the following weight proportions: The corrosion inhibitor is a mixture of benzothiazole and aminoimidazolium corrosion inhibitors.

2. The high etching factor copper etching solution according to claim 1, characterized in that, The mass ratio of the benzothiazole corrosion inhibitor to the aminoimidazolium corrosion inhibitor is 1:15-100.

3. The high etching factor copper etching solution according to claim 1, characterized in that, The benzothiazole corrosion inhibitor is one or more of 3-methyl-2(3H)-benzothiazolethion, 2(3H)-benzothiazolethion, 6-chloro-2-mercaptobenzothiazole, 5-bromo-2-mercaptobenzothiazole and 2-mercapto-6-hydroxybenzothiazole.

4. The high etching factor copper etching solution according to claim 1, characterized in that, The aminoimidazolium corrosion inhibitor is one or more of N-methyl-1H-imidazol-2-amine hydrochloride, 2-amino-1-methylimidazolium, and 1-methyl-1H-imidazol-2-amine monohydrochloride.

5. The high etching factor copper etching solution according to claim 1, characterized in that, The oxidant is phenethylamine sulfuric acid and / or a nitro compound.

6. The copper etching solution with high etching factor according to claim 1, characterized in that, The inorganic acid is one or more of nitric acid, hydrofluoric acid, sulfuric acid, and boric acid.

7. The high etching factor copper etching solution according to claim 1, characterized in that, The organic solvent is one or more of dimethyl sulfoxide, ethylene glycol, isopropanol, N,N-dimethylacrylamide, and N,N-dimethylformamide.

8. A method for preparing a copper etching solution with a high etching factor as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Weigh out the respective amounts of each component; S2. Under stirring conditions, add oxidant, inorganic acid, corrosion inhibitor and organic solvent to ultrapure water, and stir until completely dissolved to obtain the copper etching solution with high etching factor.

9. The application of a high etching factor copper etchant as described in any one of claims 1-7 in the field of encapsulated circuit board etching.

10. The application according to claim 9, characterized in that, The steps for etching the packaged circuit board using a copper etching solution with a high etch factor are as follows: Step 1: Spray the copper etching solution with high etching factor onto the surface of the packaged circuit board at 35-40℃ for 20-60 seconds. Step 2: The etched packaged circuit board is sequentially rinsed with ultrapure water, acid-washed, rinsed with ultrapure water again, and dried to complete the etching of the packaged circuit board.

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