Micro-etching and roughening solution for high-frequency and high-speed circuit board and application thereof

Abstract

The application provides a micro-etching roughening solution for high-frequency high-speed circuit boards and application thereof. The micro-etching roughening solution for high-frequency high-speed circuit boards comprises mixed acid, hydrogen peroxide, silver ions, hydrogen peroxide stabilizer, corrosion inhibitor, complexing agent and water. The mixed acid comprises sulfuric acid and nitric acid. The micro-etching roughening solution for high-frequency high-speed circuit boards can roughen copper under the condition of low micro-etching amount, has better cleaning roughening effect, forms a microstructure with a concave-convex pattern on the copper surface, and the roughness Ra value of the copper surface after treatment by the micro-etching roughening solution for high-frequency high-speed circuit boards is close to the roughness Ra value of the copper surface after treatment by a traditional sulfuric acid-hydrogen peroxide system micro-etching roughening solution, but the roughness Rz value is lower, and the transmission loss of high-frequency high-speed signals can be reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of circuit board manufacturing, and particularly relates to a micro-etching roughening solution for high-frequency high-speed circuit boards and application thereof. BACKGROUND

[0002] The miniaturization, lightness and thinness of electronic products promote the development of circuit boards in the direction of multi-layering and densification, and the reliability requirements of products are becoming higher and higher. In addition, with the development of 5G technology and other high-frequency high-speed application technologies, such as cloud servers, Ethernet, automotive radar, etc., a large amount of data transmission and high-speed signal transmission have become new demands, which promote printed circuit boards (PCB) to develop in the direction of high frequency and high speed, and the market share of high-frequency high-speed circuit boards is increasing year by year.

[0003] Due to the "skin" effect of high-frequency signals, i.e. signal transmission is concentrated on the surface layer of the conductor, when the frequency reaches 1GHz, the depth of signal transmission on the surface of the conductor is only 2.1μm, if the surface roughness of the conductor is too high, the signal transmission is only within the roughness range, resulting in a significant increase in signal transmission loss, and the higher the signal frequency, the more obvious the "skin" effect, so in order to reduce the transmission signal loss, it is necessary to reduce the surface impedance of the conductor, i.e. the surface roughness. However, in the PCB manufacturing process, in order to improve the bonding force between the copper surface and other dielectric materials such as resin, photosensitive resist layer and metal, it is usually necessary to perform micro-etching roughening treatment on the copper surface in order to avoid poor bonding between the dielectric material and the copper surface and improve the reliability.

[0004] CN115928072A discloses a copper surface micro-etching roughening solution and application thereof, the solvent of the copper surface micro-etching roughening solution includes water, the solute includes copper ions, chloride ions, organic acids, organic acid salts and 0.00001-0.007mol / L corrosion inhibitors. The copper surface micro-etching roughening solution provided by the technical solution can effectively improve the roughness of the copper surface, thereby improving the adhesion of photosensitive resist layer and dielectric materials such as ink, as well as metals such as tin, nickel, palladium and gold on the copper surface.

[0005] CN114134505A discloses a kind of alkaline microetching roughening liquid and circuit board lead roughening method, alkaline microetching roughening liquid, including A solution and B solution, the A solution component includes the following components by mass percentage concentration: alcohol amine 10%-40%, organic acid 2%-8%, corrosion inhibitor 0.15%-1%, surfactant 0.1%-0.3% and water solution 51%-86%;The B solution component includes the following components by mass percentage concentration: alcohol amine 10%-40%, organic acid 2%-8%, organic copper 1.8%-10%, corrosion inhibitor 0.1%-1%, surfactant 0.1%-0.3% and water solution 42%-86%, the technical solution provided by the alkaline microetching roughening liquid can be microetched roughening to the surface of lead frame on circuit board and reach the effect of traditional microetching roughening liquid microetching roughening.

[0006] However, the roughness Ra value of copper surface roughened by the roughening microetching liquid of the prior art is usually 0.3 μm, but the Rz value can reach 3-4 μm, and the excessively high Rz value is not conducive to signal transmission. In addition, the microetching roughening agent of the prior art needs to be used under the condition of a higher microetching amount, usually greater than 1 μm, to form a microstructure with clear concave-convex on the copper surface, which is easy to cause excessive loss of dense fine circuit copper.

[0007] Therefore, it is necessary to develop a microetching roughening liquid which can be used under the condition of a lower microetching amount, has a roughness Ra value of copper surface after roughening close to that of copper surface treated by traditional microetching roughening liquid, and has a lower surface roughness Rz value. SUMMARY

[0008] In view of the deficiencies of the prior art, the purpose of the present application is to provide a microetching roughening liquid for high-frequency high-speed circuit board and its application. The microetching roughening liquid for high-frequency high-speed circuit board can roughen copper under the condition of a low microetching amount, has a better cleaning and roughening effect, forms a microstructure with clear concave-convex on the copper surface, has a roughness Ra value of copper surface after treatment close to that of copper surface treated by traditional sulfuric acid-hydrogen peroxide system microetching roughening liquid, and has a lower surface roughness Rz value, which can reduce the transmission loss of high-frequency high-speed signal.

[0009] To achieve the purpose of the present application, the following technical solutions are adopted:

[0010] In a first aspect, the present application provides a microetching roughening liquid for high-frequency high-speed circuit board, which comprises mixed acid, hydrogen peroxide, silver ion, hydrogen peroxide stabilizer, corrosion inhibitor, complexing agent and water.

[0011] The mixed acid comprises sulfuric acid and nitric acid.

[0012] In the present application, the mixed acid, hydrogen peroxide, silver ions, hydrogen peroxide stabilizer, corrosion inhibitor, complexing agent and water are compounded to prepare a micro-etching and roughening solution for high-frequency and high-speed circuit boards, which can roughen copper under low micro-etching amount conditions, has better cleaning and roughening effect, forms a microstructure with a pleasing concave-convex on the copper surface, and the roughness Ra value of the copper surface after treatment with the micro-etching and roughening solution for high-frequency and high-speed circuit boards is close to that of the traditional sulfuric acid-hydrogen peroxide system micro-etching and roughening solution, but the surface roughness Rz value is lower, which can reduce the transmission loss of high-frequency and high-speed signals.

[0013] In the present application, the silver ions mainly have two effects: on the one hand, the silver ions can react with copper to generate silver single element in the micro-etching reaction, and the silver single element acts as an etching-resistant layer to weaken the micro-etching rate in different directions of the copper crystal; on the other hand, since the copper atoms at the grain boundaries are more active, the silver single element can be deposited at the grain boundaries faster, which weakens the difference in micro-etching rate between the crystal surface and the grain boundary, and thus reduces the corrosion depth and the vertical roughness. However, the continuous deposition of silver single element will reduce the concentration of silver ions, shorten the service life of the micro-etching and roughening solution for high-frequency and high-speed circuit boards, and excessive deposition of silver single element will result in too strong etching resistance, making it difficult to form a microstructure with a pleasing concave-convex. The purpose of adding nitric acid is that: nitric acid can not only react with copper as an oxidizing agent to accelerate the micro-etching reaction, but also react with the deposited silver single element to promote the regeneration of silver ions and prolong the service life of the micro-etching solution.

[0014] Preferably, the mass concentration ratio of sulfuric acid to nitric acid is 5-15:1, for example, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1 or 14:1, etc.

[0015] Preferably, the mass concentration of mixed acid in the micro-etching and roughening solution for high-frequency and high-speed circuit boards is 50-360 g / L, for example, 60 g / L, 80 g / L, 100 g / L, 120 g / L, 140 g / L, 160 g / L, 180 g / L, 250 g / L, 300 g / L or 350 g / L, etc.

[0016] Preferably, the mass percentage concentration of hydrogen peroxide in the hydrogen peroxide is 30-40 wt%, for example, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt% or 39 wt%, etc.

[0017] Preferably, the mass concentration of hydrogen peroxide in the micro-etching and roughening solution for high-frequency and high-speed circuit boards is 10-30 g / L, for example, 12 g / L, 14 g / L, 16 g / L, 18 g / L, 20 g / L, 22 g / L, 24 g / L, 26 g / L or 28 g / L, etc.

[0018] Preferably, the mass concentration of silver ions in the micro-etching and roughening solution for high-frequency and high-speed circuit boards is 0.001-0.02 g / L, for example, 0.002 g / L, 0.005 g / L, 0.008 g / L, 0.01 g / L, 0.013 g / L, 0.015 g / L, 0.018 g / L, or 0.019 g / L, etc.

[0019] In the present application, the mass concentration (g / L) of silver ions in the micro-etching and roughening solution for high-frequency and high-speed circuit boards = the molar concentration (mol / L) of silver ions in the micro-etching and roughening solution for high-frequency and high-speed circuit boards x 107.8682 (g / mol).

[0020] In the present application, the mass concentration of silver ions in the micro-etching and roughening solution for high-frequency and high-speed circuit boards is preferably 0.001-0.02 g / L. If the mass concentration of silver ions is too low, the elemental silver resist layer formed is dissolved too quickly, the effect of reducing the corrosion depth and reducing the vertical roughness is poor, and the roughness is high. If the mass concentration of silver ions is too high, the elemental silver is deposited in excess, and the elemental silver resist layer formed after the silver ions corrode the copper is not easy to remove, and the roughness is low.

[0021] Preferably, the mass concentration ratio of silver ions to nitric acid in the micro-etching and roughening solution for high-frequency and high-speed circuit boards is 1:750-8000, for example, 1:1000, 1:2000, 1:3000, 1:3500, 1:4000, 1:4500, 1:5000, 1:6000, 1:6500, 1:7000, or 1:7500, etc.

[0022] In the present application, the mass concentration ratio of silver ions to nitric acid in the micro-etching and roughening solution for high-frequency and high-speed circuit boards is preferably 1:750-8000. If the mass concentration ratio of silver ions to nitric acid is too large, i.e., the concentration of silver ions is relatively too high, the elemental silver resist layer formed after the silver ions corrode the copper is not easy to remove, resulting in a low micro-etching rate and low roughness. If the mass concentration ratio of silver ions to nitric acid is too small, i.e., the concentration of silver ions is relatively too low, the elemental silver resist layer formed during the etching process is dissolved too quickly and cannot function, and the copper surface roughness Rz value after micro-etching is large.

[0023] Preferably, the hydrogen peroxide stabilizer includes a morpholine compound and / or a sulfonamide compound.

[0024] Preferably, the morpholine compound includes any one or a combination of at least two of thiomorpholine, 2-aminoethyl morpholine, 4-cyclohexyl morpholine, 4-(2-hydroxyethyl) morpholine, 2-methyl morpholine, morpholine ethanesulfonic acid, or 2-morpholine acetic acid.

[0025] Preferably, the sulfonamide compound includes any one of N-(2-aminoethyl)-4- methylbenzenesulfonamide, 4-hydroxybenzenesulfonamide, p-toluenesulfonylurea, 4-(2- aminoethyl)benzenesulfonamide, 2-thiophenesulfonamide, or 5-amino-2-methylbenzenesulfonamide or a combination of at least two thereof.

[0026] Preferably, the mass concentration of the hydrogen peroxide stabilizer in the micro-etching and roughening solution for high-frequency and high-speed circuit boards is 0.5-10 g / L, such as 0.6 g / L, 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L, or 9 g / L, etc.

[0027] Preferably, the corrosion inhibitor includes a thiazole derivative.

[0028] Preferably, the thiazole derivative includes any one of 2-amino-4-isopropyl-5- chlorothiazole, 5-amino-2-chlorothiazole-5-carboxylic acid, 2-(2,5-dichlorothiazol-4- yl)acetic acid, 2-amino-3-(2,5-dichlorothiazol-4-yl)propanoic acid, 2-(2,5-dichlorothiazol- 4-yl)ethan-1 -amine, N-(2-(2-amino-5-chlorothiazol-4-yl)ethyl)acetamide, 2-(2- chlorothiazol-4-yl)-2-oxoacetic acid, 4-amino-2-chlorothiazole-5-carboxylic acid, (2- chloro-thiazol-5-methyl)-methyl-amine, 2-chloro-4-aminomethylthiazole, 2-amino-5- bromothiazole, 2-methoxymethyl-5-chloromethylthiazole, 2-amino-4-chloromethylthiazole, or 5-(2-chloroethyl)thiazol-2-amine or a combination of at least two thereof.

[0029] Preferably, the mass concentration of the corrosion inhibitor in the micro-etching and roughening solution for high-frequency and high-speed circuit boards is 0.5-2 g / L, such as 0.6 g / L, 0.7 g / L, 0.9 g / L, 1 g / L, 1.2 g / L, 1.3 g / L, 1.5 g / L, 1.7 g / L, 1.8 g / L, or 1.9 g / L, etc.

[0030] Preferably, the mass concentration ratio of the corrosion inhibitor to silver ions in the micro-etching and roughening solution for high-frequency and high-speed circuit boards is 50-500:1, such as 60:1, 80:1, 100:1, 150:1, 200:1, 250:1, 300:1, 350:1, 400:1, or 450:1, etc.

[0031] In the present application, there is interaction between the silver ions and the corrosion inhibitor, and there is difference in activity between the copper crystal surface and the grain boundary in the micro-etching reaction process, the copper activity is stronger at the grain boundary, and the micro-etching rate is faster, after adding the corrosion inhibitor, the corrosion inhibitor is preferentially adsorbed on the copper crystal surface, further enlarging the difference in corrosion rate between the grain boundary and the crystal surface, thereby causing the crystal to be etched too deeply in the vertical direction and the roughness to be too large; after adding the silver ions, on the one hand, the silver ions can react with copper as an oxidizing agent and generate elemental silver corrosion-resistant layer, and the reaction rate is fast at the grain boundary, so that the elemental silver corrosion-resistant layer can be quickly formed at the grain boundary to inhibit corrosion at the grain boundary; on the other hand, the silver ions can interact with N, S and other atoms in the corrosion inhibitor molecules to form a passivation film adsorbed on the copper surface, further inhibiting vertical corrosion, thereby avoiding over-etching.

[0032] In the present application, the mass concentration ratio of the corrosion inhibitor to the silver ions in the micro-etching roughening solution for high-frequency high-speed circuit boards is preferably 50-500:1, if the mass concentration ratio of the corrosion inhibitor to the silver ions is too large, that is, the concentration of the corrosion inhibitor is too high, the micro-etching rate will be significantly reduced, and a high concentration of the corrosion inhibitor may result in less difference in adsorption amount between the copper surface and the grain boundary, so that a microstructure with clear concave-convex cannot be formed, and a high concentration of the corrosion inhibitor will also result in a thick passivation film formed by the reaction of the corrosion inhibitor with the silver ions and copper ions, a long passivation film breaking time, and a significant reduction in the micro-etching rate, so that it is difficult for the copper surface after micro-etching to form a microstructure with clear concave-convex, thereby resulting in a low roughness value; if the mass concentration ratio of the corrosion inhibitor to the silver ions is too small, the passivation layer formed by the reaction of the corrosion inhibitor with the silver ions is thin and breaks quickly, which is not conducive to inhibiting vertical corrosion, and a low concentration of the corrosion inhibitor also cannot ensure effective roughening effect to form a microstructure with clear concave-convex on the copper surface.

[0033] Preferably, the complexing agent comprises a compound containing a carboxylic acid group and / or an amino group.

[0034] In the present application, the complexing agent comprises a compound containing a carboxylic acid group and / or an amino group, which is a multidentate ligand containing multiple coordination atoms such as N, O and P in the molecule, can effectively complex copper ions or silver ions, prevent the copper ion concentration from being too high to accelerate the self-decomposition of hydrogen peroxide, and stabilize the micro-etching rate.

[0035] Preferably, the compound containing a carboxylic acid group and / or an amino group comprises any one or a combination of at least two of 2-aminonicotinic acid, 4-aminopyridine, 2-amino-4-methylpyridine, 2-phosphonobutane-1,2,4-tricarboxylic acid, sodium nitrilotriacetate or hydroxyethyl ethylenediamine triacetate.

[0036] Preferably, the mass concentration of the complexing agent in the micro-etching roughening solution for high-frequency high-speed circuit boards is 1-10 g / L, such as 1.5 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L, or 9 g / L, etc.

[0037] Preferably, the mass concentration ratio of the complexing agent to silver ions in the micro-etching roughening solution for high-frequency high-speed circuit boards is 200-1000:1.

[0038] In the present application, the mass concentration ratio of the complexing agent to silver ions in the micro-etching roughening solution for high-frequency high-speed circuit boards is preferably 200-1000:1. If the mass concentration ratio of the complexing agent to silver ions is too large, i.e., the concentration of the complexing agent is too high, most of the silver ions in the micro-etching roughening solution for high-frequency high-speed circuit boards exist in the form of silver complexes, so it is difficult to form a single silver resist layer, thereby failing to inhibit longitudinal corrosion. If the mass concentration ratio of the complexing agent to silver ions is too small, i.e., the concentration of the complexing agent is too low, during the micro-etching process, the single silver resist layer can be quickly formed, resulting in too strong resist effect. At the same time, the rapid generation of the single silver resist layer leads to a rapid reduction in the concentration of silver ions in the micro-etching roughening solution for high-frequency high-speed circuit boards, thereby shortening the service life of the micro-etching roughening solution for high-frequency high-speed circuit boards.

[0039] Preferably, the water comprises deionized water.

[0040] In a second aspect, the present application provides a use of the micro-etching roughening solution for high-frequency high-speed circuit boards according to the first aspect in the manufacture of circuit boards.

[0041] Preferably, the circuit board is a high-frequency high-speed board.

[0042] Preferably, the use comprises a use of the micro-etching roughening solution for high-frequency high-speed circuit boards according to the first aspect in the dry film pretreatment or the solder mask pretreatment in the manufacturing process of high-frequency high-speed boards.

[0043] Compared with the prior art, the present application has the following beneficial effects:

[0044] The micro-etching roughening liquid for high-frequency high-speed circuit board can roughen copper under the condition of 0.5-0.7 μm micro-etching amount, has a better cleaning roughening effect, forms a microstructure with a pleasing concave-convex on the copper surface, enhances the bonding force between the copper surface and the medium material, and further improves the product yield and reliability. In addition, the roughness Ra value of the copper surface after the treatment of the micro-etching roughening liquid for high-frequency high-speed circuit board is close to that of the traditional sulfuric acid-hydrogen peroxide system micro-etching roughening liquid, but the roughness Rz value is 30%-70% lower than that of the traditional sulfuric acid-hydrogen peroxide system micro-etching roughening liquid, which can reduce the transmission loss of high-frequency high-speed signals. The micro-etching rate of the micro-etching roughening liquid for high-frequency high-speed circuit board is 0.5-0.89 μm / min, the micro-etching amount is 0.55-0.7 μm, the roughness Ra value is 0.17-0.35 μm, and the roughness Rz value is 1.42-2.7 μm. In a preferred case, the micro-etching amount of the micro-etching roughening liquid for high-frequency high-speed circuit board is 0.55-0.7 μm, the roughness Ra value is 0.27-0.35 μm, and the roughness Rz value is 1.52-1.82 μm. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 SEM image of the copper surface after the treatment of the micro-etching roughening liquid for high-frequency high-speed circuit board provided in Example 1;

[0046] Figure 2 SEM image of the copper surface after the treatment of the micro-etching roughening liquid for high-frequency high-speed circuit board provided in Example 4;

[0047] Figure 3 SEM image of the copper surface after the treatment of the micro-etching roughening liquid for high-frequency high-speed circuit board provided in Example 5;

[0048] Figure 4 SEM image of the copper surface after the treatment of the micro-etching roughening liquid for high-frequency high-speed circuit board provided in Example 6;

[0049] Figure 5 SEM image of the copper surface after the treatment of the micro-etching roughening liquid for high-frequency high-speed circuit board provided in Example 7;

[0050] Figure 6 SEM image of the copper surface after the treatment of the micro-etching roughening liquid for high-frequency high-speed circuit board provided in Example 8;

[0051] Figure 7 SEM image of the copper surface after the treatment of the micro-etching roughening liquid for high-frequency high-speed circuit board provided in Example 9;

[0052] Figure 8 SEM image of the copper surface after the treatment of the micro-etching roughening liquid for high-frequency high-speed circuit board provided in Comparative Example 1;

[0053] Figure 9 SEM image of the copper surface treated by the micro-etching roughening solution for high-frequency high-speed circuit board provided in Comparative Example 2. DETAILED DESCRIPTION

[0054] The technical solutions of the present application will be further illustrated by specific embodiments. Those skilled in the art should understand that the embodiments are only to help understand the present application and should not be regarded as specific limitations of the present application.

[0055] Example 1

[0056] The present embodiment provides a micro-etching roughening solution for high-frequency high-speed circuit board and a preparation method thereof. The components of the micro-etching roughening solution for high-frequency high-speed circuit board are as follows in terms of mass concentration: sulfuric acid (50wt% in mass percentage) 140g / L, nitric acid (67wt% in mass percentage) 15g / L, hydrogen peroxide (35wt% in mass percentage) 30g / L, silver ion (silver ion is derived from silver acetate) 0.01g / L, hydrogen peroxide stabilizer (thiomorpholine and 2-thiophenesulfonamide in a mass ratio of 4:1) 0.01g / L, corrosion inhibitor (5-amino-2-chlorothiazole-5-carboxylic acid) 2g / L, complexing agent (2-phosphonobutane-1,2,4-tricarboxylic acid) 5g / L, and solvent is deionized water.

[0057] In the micro-etching roughening solution for high-frequency high-speed circuit board, the mass concentration ratio of sulfuric acid and nitric acid is 9.3:1; the mass concentration ratio of silver ion and nitric acid is 1:1500; the mass concentration ratio of corrosion inhibitor and silver ion is 200:1; and the mass concentration ratio of complexing agent and silver ion is 500:1.

[0058] The preparation method of the micro-etching roughening solution for high-frequency high-speed circuit board is as follows: sulfuric acid, nitric acid, hydrogen peroxide, silver ion, hydrogen peroxide stabilizer, corrosion inhibitor, complexing agent, and water are mixed according to the above-mentioned formulation amount, and stirred to obtain the micro-etching roughening solution for high-frequency high-speed circuit board.

[0059] Example 2

[0060] The embodiment provides a micro-etching roughening solution for high-frequency high-speed circuit boards and a preparation method thereof. The micro-etching roughening solution for high-frequency high-speed circuit boards comprises the following components in terms of mass concentration: 120 g / L of sulfuric acid (50wt% in mass percentage), 8 g / L of nitric acid (67wt% in mass percentage), 30 g / L of hydrogen peroxide (35wt% in mass percentage), 0.001 g / L of silver ions (the silver ions are derived from silver nitrate), 0.5 g / L of hydrogen peroxide stabilizer (2-aminoethyl morpholine and 4-hydroxybenzenesulfonamide in a mass ratio of 4:1), 0.5 g / L of corrosion inhibitor (5-amino-2-chlorothiazole-5-carboxylic acid), 1 g / L of complexing agent (4-aminopyridine), and deionized water as a solvent.

[0061] In the micro-etching roughening solution for high-frequency high-speed circuit boards, the mass concentration ratio of the sulfuric acid and the nitric acid is 15:1; the mass concentration ratio of the silver ions and the nitric acid is 1:8000; the mass concentration ratio of the corrosion inhibitor and the silver ions is 500:1; and the mass concentration ratio of the complexing agent and the silver ions is 1000:1.

[0062] The preparation method of the micro-etching roughening solution for high-frequency high-speed circuit boards comprises the following steps: mixing sulfuric acid, nitric acid, hydrogen peroxide, silver ions, hydrogen peroxide stabilizer, corrosion inhibitor, complexing agent and water according to the above-mentioned formula, and stirring to obtain the micro-etching roughening solution for high-frequency high-speed circuit boards.

[0063] Embodiment 3

[0064] The embodiment provides a micro-etching roughening solution for high-frequency high-speed circuit boards and a preparation method thereof. The micro-etching roughening solution for high-frequency high-speed circuit boards comprises the following components in terms of mass concentration: 300 g / L of sulfuric acid (50wt% in mass percentage), 60 g / L of nitric acid (67wt% in mass percentage), 30 g / L of hydrogen peroxide (35wt% in mass percentage), 0.02 g / L of silver ions (the silver ions are derived from silver methanesulfonate), 10 g / L of hydrogen peroxide stabilizer (thiomorpholine and 2-thiophenesulfonamide in a mass ratio of 4:1), 1 g / L of corrosion inhibitor (5-amino-2-chlorothiazole-5-carboxylic acid), 10 g / L of complexing agent (hydroxyethyl ethylene diamine triacetic acid), and deionized water as a solvent.

[0065] In the micro-etching roughening solution for high-frequency high-speed circuit boards, the mass concentration ratio of the sulfuric acid and the nitric acid is 5:1; the mass concentration ratio of the silver ions and the nitric acid is 1:3000; the mass concentration ratio of the corrosion inhibitor and the silver ions is 50:1; and the mass concentration ratio of the complexing agent and the silver ions is 500:1.

[0066] The preparation method of the micro-etching roughening solution for high-frequency high-speed circuit boards is as follows: the sulfuric acid, nitric acid, hydrogen peroxide, silver ions, hydrogen peroxide stabilizer, corrosion inhibitor, complexing agent and water are mixed according to the above formula, and stirred to obtain the micro-etching roughening solution for high-frequency high-speed circuit boards.

[0067] Example 4

[0068] The embodiment provides a micro-etching roughening solution for high-frequency high-speed circuit boards and a preparation method thereof, which are different from those in example 1 only in that 5-amino-2-chlorothiazole-5-carboxylic acid is replaced by 2-amino-5-bromothiazole with the same mass, and the rest is the same as in example 1.

[0069] Example 5

[0070] The embodiment provides a micro-etching roughening solution for high-frequency high-speed circuit boards and a preparation method thereof, which are different from those in example 1 only in that 5-amino-2-chlorothiazole-5-carboxylic acid is replaced by 5-amino-2-chlorothiazole-5-carboxylic acid and N-(2-(2-amino-5-chlorothiazole-4-yl)ethyl) acetamide with the same mass and a mass concentration ratio of 1:2, and the rest is the same as in example 1.

[0071] Example 6

[0072] The embodiment provides a micro-etching roughening solution for high-frequency high-speed circuit boards and a preparation method thereof, which are different from those in example 1 only in that 5-amino-2-chlorothiazole-5-carboxylic acid is replaced by 2-amino-5-bromothiazole and 2-amino-4-chloromethylthiazole with the same mass and a mass concentration ratio of 3:1, and the rest is the same as in example 1.

[0073] Example 7

[0074] The embodiment provides a micro-etching roughening solution for high-frequency high-speed circuit boards and a preparation method thereof, which are different from those in example 1 only in that thiomorpholine and 2-thiophenesulfonamide with a mass concentration ratio of 4:1 are replaced by morpholine ethanesulfonic acid and N-(2-aminoethyl)-4-methylbenzenesulfonamide with a mass of 1:1, and the rest is the same as in example 1.

[0075] Example 8

[0076] The embodiment provides a micro-etching roughening solution for high-frequency high-speed circuit boards and a preparation method thereof, which are different from those in example 1 only in that the mass concentration of silver ions is adjusted to 0.005 g / L, the mass concentration ratio of the silver ions and nitric acid in the micro-etching roughening solution for high-frequency high-speed circuit boards is changed to 1:3000, the mass concentration ratio of the corrosion inhibitor and silver ions is changed to 400:1, and the mass concentration ratio of the complexing agent and silver ions is 1000:1, and the rest is the same as in example 1.

[0077] Example 9

[0078] The embodiment provides a micro-etching roughening solution for high-frequency high-speed circuit boards and a preparation method thereof, which are different from the embodiment 1 only in that the mass concentration of silver ions is adjusted to be 0.015 g / L, the mass concentration of the corrosion inhibitor is adjusted to be 1.5 g / L, and the mass of the complexing agent is adjusted to be 3 g / L, the mass concentration ratio of the silver ions and nitric acid in the micro-etching roughening solution for high-frequency high-speed circuit boards is changed to be 1:1000, the mass concentration ratio of the corrosion inhibitor and the silver ions is changed to be 100:1, and the mass concentration ratio of the complexing agent and the silver ions is 200:1, and the rest is the same as the embodiment 1.

[0079] Embodiment 10

[0080] The embodiment provides a micro-etching roughening solution for high-frequency high-speed circuit boards and a preparation method thereof, which are different from the embodiment 1 only in that the mass concentration of silver ions is adjusted to be 0.03 g / L, the mass concentration ratio of the silver ions and nitric acid in the micro-etching roughening solution for high-frequency high-speed circuit boards is changed to be 1:500, the mass concentration ratio of the corrosion inhibitor and the silver ions is changed to be 67:1, and the mass concentration ratio of the complexing agent and the silver ions is 167:1, and the rest is the same as the embodiment 1.

[0081] Embodiment 11

[0082] The embodiment provides a micro-etching roughening solution for high-frequency high-speed circuit boards and a preparation method thereof, which are different from the embodiment 1 only in that the mass concentration of silver ions is adjusted to be 0.0005 g / L, the mass concentration ratio of the silver ions and nitric acid in the micro-etching roughening solution for high-frequency high-speed circuit boards is changed to be 1:300, the mass concentration ratio of the corrosion inhibitor and the silver ions is changed to be 40:1, and the mass concentration ratio of the complexing agent and the silver ions is 100:1, and the rest is the same as the embodiment 1.

[0083] Embodiment 12

[0084] The embodiment provides a micro-etching roughening solution for high-frequency high-speed circuit boards and a preparation method thereof, which are different from the embodiment 1 only in that the mass concentration of the corrosion inhibitor is adjusted to be 0.4 g / L, the mass concentration ratio of the corrosion inhibitor and the silver ions in the micro-etching roughening solution for high-frequency high-speed circuit boards is changed to be 40:1, and the rest is the same as the embodiment 1.

[0085] Embodiment 13

[0086] The embodiment provides a micro-etching roughening solution for high-frequency high-speed circuit boards and a preparation method thereof, which are different from the embodiment 1 only in that the mass concentration of nitric acid (the concentration is 67 wt%) is adjusted to be 5 g / L, the mass concentration ratio of the silver ions and nitric acid in the micro-etching roughening solution for high-frequency high-speed circuit boards is changed to be 1:500, and the rest is the same as the embodiment 1.

[0087] Comparative Example 1

[0088] The comparative example provides a micro-etching roughening solution for high-frequency high-speed circuit boards and a preparation method thereof, which is only different from example 1 in that no nitric acid is added to the micro-etching roughening solution for high-frequency high-speed circuit boards, the mass concentration of sulfuric acid is adjusted to 155 g / L, and the others are the same as example 1.

[0089] Comparative Example 2

[0090] The comparative example provides a micro-etching roughening solution for high-frequency high-speed circuit boards and a preparation method thereof, which is only different from example 1 in that no silver ions are added to the micro-etching roughening solution for high-frequency high-speed circuit boards, and the others are the same as example 1.

[0091] Comparative Example 3

[0092] The comparative example provides a micro-etching roughening solution for high-frequency high-speed circuit boards and a preparation method thereof, which is only different from example 1 in that no complexing agent is added to the micro-etching roughening solution for high-frequency high-speed circuit boards, and the others are the same as example 1.

[0093] Comparative Example 4

[0094] The comparative example provides a micro-etching roughening solution for high-frequency high-speed circuit boards and a preparation method thereof, which is only different from example 1 in that the micro-etching roughening solution for high-frequency high-speed circuit boards is a sulfuric acid-hydrogen peroxide system micro-etching roughening solution SkyRuff 155A from Shanghai Tiancheng Chemical Co., Ltd.

[0095] The micro-etching roughening solutions for high-frequency high-speed circuit boards provided by the examples and comparative examples are subjected to the following performance tests.

[0096] (1) Micro-etching rate determination: the micro-etching roughening solutions for high-frequency high-speed circuit boards provided by examples 1-13 and comparative examples 1-4 are transferred to a spraying machine, respectively, then 17 pieces of copper-clad substrates (10 cm x 10 cm) are taken, the copper-clad substrates are subjected to acid pickling with an aqueous solution of sulfuric acid (H2SO4 mass percentage concentration is 50 wt%) with a mass concentration of 140 g / L, the surface is cleaned by water washing, then the copper-clad substrates are tested under spraying conditions, after the spraying is completed, the copper-clad substrates are cleaned with deionized water, and after drying, the mass of the copper-clad substrates before and after spraying is recorded as m1 and m2, respectively, and the micro-etching rate is calculated. During the spraying process, the temperature of the micro-etching roughening solution for high-frequency high-speed circuit boards is 30°C, the spraying pressure is 1 kg / cm 2 , the spraying time is 1 minute; the calculation formula of the micro-etching rate is as follows.

[0097] Micro-etching rate = (m1-m2) / (S x p) x 10000;

[0098] Wherein, m1, m2 are the mass of copper-clad plate before and after spraying micro-etching treatment with the micro-etching solution for high-frequency high-speed circuit board, respectively (unit: g); S is the area of copper-clad plate (S = 10 x 10 x 2 = 200 cm 2 ), and p is the density of copper, taken as 8.96 g / cm 3 .

[0099] (2) Micro-etching amount: Micro-etching amount = micro-etching rate x spraying time. The micro-etching amount of Examples 1-13 and Comparative Examples 1-3 is controlled in the range of 0.5-0.7 pm; the micro-etching amount of Comparative Example 4 is controlled in the range of 0.9-1.1 pm.

[0100] (3) Roughness: The roughness Ra value and Rz value of the surface of the copper-clad substrate treated with the micro-etching solution for high-frequency high-speed circuit board are obtained by 3D laser microscope testing.

[0101] (4) Micro-morphology determination: The micro-morphology of the surface of the copper-clad substrate treated with the micro-etching solution for high-frequency high-speed circuit board is obtained by scanning electron microscope (SEM) testing.

[0102] The test results are shown in Table 1.

[0103] Table 1

[0104]

[0105]

[0106] According to the test results in Table 1, the micro-etching rate of the micro-etching solution for high-frequency high-speed circuit board provided by Examples 1-13 is 0.5-0.89 pm / min, the micro-etching amount is 0.55-0.7 pm, the roughness Ra value is 0.17-0.35 pm, and the roughness Rz value is 1.42-2.7 pm.

[0107] The copper surface treated with the micro-etching solution for high-frequency high-speed circuit board provided by Examples 1 and 4-6 can form a microstructure with a clear concave-convex structure, as shown in Figures 1-4 According to the test results in Table 1, when the corrosion inhibitor is replaced by other thiazole derivatives, the fluctuation range of Ra value is 0.3-0.35 pm, and the fluctuation range of Rz value is 1.52-1.74 pm.

[0108] The silver ion concentration, nitric acid, corrosion inhibitor, and mass concentration ratio of complexing agent to silver ion in the micro-etching solution for high-frequency high-speed circuit board provided by Examples 1-3 and Examples 8-9 are all within a specific range, the micro-etching rate of the micro-etching solution for high-frequency high-speed circuit board has little difference, and the micro-morphology of the copper surface of the treated copper-clad substrate has no significant difference, as shown in Figure 1 and Figures 6-7However, there are slight differences between the roughness Ra and roughness Rz values. The Ra value fluctuates between 0.27 and 0.34 μm, while the Rz value fluctuates between 1.58 and 1.82 μm.

[0109] The micro-etching amount of the micro-etching and roughening liquid for high-frequency and high-speed circuit boards provided in Examples 1-9 is 0.55-0.7 μm, the roughness Ra value is 0.27-0.35 μm, and the roughness Rz value is 1.52-1.82 μm.

[0110] Compared with Example 1, if the mass concentration of silver ions is too high (Example 10), the roughness Ra and roughness Rz values ​​are low, and the copper surface treated with micro-etching roughening solution for high-frequency and high-speed circuit boards cannot form a textured microstructure. This roughness is difficult to meet the requirements of pre-soldering treatment for printed circuit boards, and poor bonding between the dielectric material and the copper surface is likely to occur. If the mass concentration of silver ions is too low (Example 11), the effect of silver ions is not significant, and the surface roughness Ra and Rz values ​​of copper surface treated with micro-etching roughening solution for high-frequency and high-speed circuit boards are both high, proving that the performance is better when the mass concentration of silver ions in the micro-etching roughening solution for high-frequency and high-speed circuit boards is within a specific range.

[0111] Compared with Example 1, if the mass concentration of the corrosion inhibitor is too low (Example 12), the mass concentration ratio of the corrosion inhibitor to silver ions is too low, the micro-etching rate is slightly lower, and the roughness Ra value of the treated copper surface is relatively low, while the roughness Rz value is significantly higher. This proves that the performance is better when the mass concentration ratio of the corrosion inhibitor to silver ions in the micro-etching roughening solution for high-frequency and high-speed circuit boards is within a specific range.

[0112] Compared with Example 1, if the mass concentration of nitric acid is too low (Example 13), the mass concentration ratio of silver ions to nitric acid is too high, resulting in a lower micro-etching rate. After treatment, the roughness values ​​Ra and Rz of the copper surface are both lower, proving that the performance is better when the mass concentration ratio of silver ions to nitric acid in the micro-etching roughening solution for high-frequency and high-speed circuit boards is within a specific range.

[0113] Compared with Example 1, without the addition of nitric acid (Comparative Example 1), the micro-etching rate is very low, the roughening effect on the copper surface is poor, and the roughness value is low. Figure 8 As shown, this is due to the inability to effectively remove the resist layer during the micro-etching process.

[0114] Compared with Example 1, without the addition of silver ions (Comparative Example 2), the surface roughness Rz of the treated copper was significantly higher, reaching 2.88 μm. Figure 9 As shown, this is because when the micro-etching and roughening solution used for high-frequency and high-speed circuit boards does not contain silver ions, it cannot form an effective anti-corrosion layer to inhibit longitudinal corrosion.

[0115] Compared with Example 1, if no complexing agent is added (Comparative Example 3), the micro-etching rate, roughness Ra value and roughness Rz value are all low, because when the micro-etching roughening solution does not contain a complexing agent, silver ions quickly form a elemental silver resist layer and the thickness is high, which is difficult to remove, and seriously inhibits the corrosion of the copper by the micro-etching roughening solution for high-frequency high-speed circuit boards, so the micro-etching rate is low and the surface roughness is low.

[0116] Compared with Example 1, if the micro-etching roughening solution SkyRuff 155A (Comparative Example 4) is used, the roughness Ra and roughness Rz are significantly higher, reaching 0.41 μm and 3.74 μm respectively, which is not conducive to the transmission of high-frequency high-speed signals.

[0117] The applicant states that the process of the present application is illustrated by the above examples, but the present application is not limited to the above process steps, i.e. it does not mean that the present application must rely on the above process steps to be implemented. It should be understood by those skilled in the art that any improvement on the present application, equivalent replacement of the materials selected by the present application, addition of auxiliary ingredients, selection of specific methods, etc. all fall within the scope of protection and disclosure of the present application.

Claims

1. A micro-etching and roughening solution for high-frequency and high-speed circuit boards, characterized in that, The micro-etching and roughening solution for high-frequency and high-speed circuit boards includes a mixed acid, hydrogen peroxide, silver ions, hydrogen peroxide stabilizer, corrosion inhibitor, complexing agent, and water. The mixed acid includes sulfuric acid and nitric acid; The mass ratio of sulfuric acid to nitric acid is 5-15:1; The mass concentration of the silver ions is 0.001-0.02 g / L; The mass concentration ratio of silver ions to nitric acid is 1:750-8000; The mass concentration ratio of corrosion inhibitor to silver ions in the micro-etching and roughening solution for high-frequency and high-speed circuit boards is 50-500:

1. The mass concentration ratio of complexing agent to silver ions in the micro-etching roughening solution for high-frequency and high-speed circuit boards is 200-1000:

1.

2. The micro-etching and roughening solution for high-frequency and high-speed circuit boards according to claim 1, characterized in that, The mass concentration of the mixed acid in the micro-etching and roughening solution for high-frequency and high-speed circuit boards is 50-360 g / L.

3. The micro-etching and roughening solution for high-frequency and high-speed circuit boards according to claim 1, characterized in that, The hydrogen peroxide concentration in the hydrogen peroxide solution is 30-40 wt%.

4. The micro-etching and roughening solution for high-frequency and high-speed circuit boards according to claim 3, characterized in that, The hydrogen peroxide concentration in the micro-etching and roughening solution for high-frequency and high-speed circuit boards is 10-30 g / L.

5. The micro-etching and roughening solution for high-frequency and high-speed circuit boards according to claim 1, characterized in that, The hydrogen peroxide stabilizer includes morpholine compounds and / or sulfonamide compounds.

6. The micro-etching and roughening solution for high-frequency and high-speed circuit boards according to claim 5, characterized in that, The morpholine compounds include any one or a combination of at least two of the following: thiomorpholine, 2-aminoethylmorpholine, 4-cyclohexylmorpholine, 4-(2-hydroxyethyl)morpholine, 2-methylmorpholine, morpholine ethanesulfonic acid, or 2-morpholine acetic acid.

7. The micro-etching and roughening solution for high-frequency and high-speed circuit boards according to claim 5, characterized in that, The sulfonamide compounds include any one or a combination of at least two of N-(2-aminoethyl)-4-methylbenzenesulfonamide, 4-hydroxybenzenesulfonamide, p-toluenesulfonylurea, 4-(2-aminoethyl)benzenesulfonamide, 2-thiophenesulfonamide or 5-amino-2-methylbenzenesulfonamide.

8. The micro-etching and roughening solution for high-frequency and high-speed circuit boards according to claim 5, characterized in that, The mass concentration of hydrogen peroxide stabilizer in the micro-etching and roughening solution for high-frequency and high-speed circuit boards is 0.5-10 g / L.

9. The micro-etching and roughening solution for high-frequency and high-speed circuit boards according to claim 1, characterized in that, The corrosion inhibitor includes thiazole derivatives.

10. The micro-etching and roughening solution for high-frequency and high-speed circuit boards according to claim 9, characterized in that, The thiazole derivatives include any one or a combination of at least two of the following: 2-amino-4-isopropyl-5-chlorothiazole, 5-amino-2-chlorothiazole-5-carboxylic acid, 2-(2,5-dichlorothiazole-4-yl)acetic acid, 2-amino-3-(2,5-dichlorothiazole-4-yl)propionic acid, 2-(2,5-dichlorothiazole-4-yl)ethyl-1-amine, N-(2-(2-amino-5-chlorothiazole-4-yl)ethyl)acetamide, 2-(2-chlorothiazole-4-yl)-2-oxoacetic acid, 4-amino-2-chlorothiazole-5-carboxylic acid, (2-chloro-thiazole-5-methyl)-methyl-amine, 2-chloro-4-aminomethylthiazole, 2-amino-5-bromothiazole, 2-methoxymethyl-5-chloromethylthiazole, 2-amino-4-chloromethylthiazole, or 5-(2-chloroethyl)thiazole-2-amine.

11. The micro-etching and roughening solution for high-frequency and high-speed circuit boards according to claim 9, characterized in that, The mass concentration of the corrosion inhibitor in the micro-etching and roughening solution for high-frequency and high-speed circuit boards is 0.5-2 g / L.

12. The micro-etching and roughening solution for high-frequency and high-speed circuit boards according to claim 1, characterized in that, The complexing agent includes compounds containing carboxylic acid groups and / or amino groups.

13. The micro-etching and roughening solution for high-frequency and high-speed circuit boards according to claim 12, characterized in that, The compound containing a carboxylic acid group and / or an amino group includes any one or a combination of at least two of 2-aminonicotinic acid, 4-aminopyridine, 2-amino-4-methylpyridine, 2-phosphonobutane-1,2,4-tricarboxylic acid, sodium azirmonotriacetate, or hydroxyethylethylenediaminetriacetic acid.

14. The micro-etching and roughening solution for high-frequency and high-speed circuit boards according to claim 12, characterized in that, The mass concentration of the complexing agent in the micro-etching and roughening solution for high-frequency and high-speed circuit boards is 1-10 g / L.

15. The application of the micro-etching and roughening solution for high-frequency and high-speed circuit boards according to any one of claims 1-14 in circuit board manufacturing.

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