Micro-etching super-roughening liquid for enhancing binding force of PCB copper surface and resin and application of micro-etching super-roughening liquid

Abstract

The invention discloses a micro-etching and super-roughening solution for enhancing the binding force of a PCB copper surface and resin and application of the micro-etching and super-roughening solution, and relates to the technical field of PCB machining, the copper surface micro-etching and super-roughening solution takes water as a solvent, and solutes comprise copper ions, chloride ions, organic acid, organic acid salt and 100-400 ppm of an azole corrosion inhibitor; the azoles corrosion inhibitor is selected from at least one of 1-hydroxybenzotriazole, 3, 5-diamino-1, 2, 4-triazole, 2-aminobenzimidazole, tetrazole or 3-amino-5-methylthio-1H-1, 2, 4-triazole, and the corrosion inhibitor is selected from at least one of 1-hydroxybenzotriazole, 3, 5-diamino-1, 2, 4-triazole, 2-aminobenzimidazole, tetrazole or 3-amino-5-methylthio-1H-1, 2, 4-triazole. According to the surface micro-etching super-roughening liquid, a specific micro-etching system is combined with a specific azole corrosion inhibitor, so that selective corrosion of a copper surface is achieved, a more rugged shape is formed, the contact area is increased, and the interface bonding force of copper and resin is improved.

Description

Technical Field

[0001] The invention relates to the technical field of PCB board processing, and in particular to a micro-etching super-roughening liquid for enhancing the bonding force between a PCB copper surface and a resin and an application thereof. Background Art

[0002] With the continuous improvement of chip manufacturing and packaging technology, the space compression effect of electronic equipment motherboards is significant, which has prompted the evolution of printed circuit boards (PCBs) towards lightweight, thin, and miniaturization. This technological evolution has directly led to a significant increase in PCB line density, and the line width and line spacing parameters have continued to decrease, resulting in a sharp decrease in the contact area between the line and the prepreg, posing a severe challenge to the copper-resin interface bonding strength.

[0003] The mechanical interlocking mechanism is an effective method to enhance the copper-resin interface bonding strength. Its mechanism of action originates from the penetration and solidification of the molten polymer in the microporous structure of the metal matrix surface, forming an interlocking hook-shaped topological structure. Existing studies have shown that the interface bonding performance can be effectively improved by optimizing the geometric parameters of mechanical interlocking (such as pore depth, pore size distribution and specific surface area). In order to optimize the surface structure of the copper surface, the current mainstream surface treatment technologies include: mechanical polishing, chemical etching, anodizing, conversion coating and laser irradiation. Chemical etching is low in cost, The traditional copper surface roughening process is achieved through a sulfuric acid-hydrogen peroxide system, but the solution system is generally stable and easily deteriorates; and roughening through it is prone to excessive corrosion of the copper substrate, uncontrollable surface microstructure, and affects the copper-resin interface bonding strength (usually ≤0.7 kN / m). Some products in the existing technology will add corrosion inhibitors (such as benzotriazoles), which can inhibit excessive corrosion of the roughening agent, but will reduce the surface roughness, resulting in a lack of significant improvement in bonding strength. The copper-resin interface bonding strength improvement range of such products is basically below 20%.

[0004] Patent CN115928072A proposes a copper surface micro-etching roughening liquid and its application. On the one hand, it can effectively improve the roughness of the copper surface, thereby improving the adhesion of photosensitive resists and dielectric materials such as inks and metals such as tin, nickel, palladium and gold on the copper surface; on the other hand, it has better micro-etching and roughening effects on copper surfaces with different copper crystals, and has a wide range of applications. Although the adhesion of the treated copper surface to ink is significantly improved, the roughness of the copper surface (Ra value is 0.36~0.43μm) is low, and the interface bonding force to the resin system is limited; it is necessary to develop a new roughening liquid that can effectively improve the copper-resin interface bonding force. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects and shortcomings of the existing copper surface treatment process and provide a copper surface micro-etching super-roughening liquid, which is beneficial to improving the copper-resin interface bonding force.

[0006] Another object of the present invention is to provide a copper surface micro-etching and roughening solution for use in the manufacture of printed circuit boards.

[0007] Another object of the present invention is to provide a manufacturing process for a copper-clad laminated PCB substrate.

[0008] The above-mentioned purpose of the present invention is achieved through the following technical solutions: The present invention provides a copper surface micro-etching and ultra-roughening solution, which uses water as a solvent and contains copper ions, chloride ions, organic acids, organic acid salts and 100-400 ppm of azole corrosion inhibitors; The azole corrosion inhibitor is selected from at least one of 1-hydroxybenzotriazole, 3,5-diamino-1,2,4-triazole, 2-aminobenzimidazole, tetrazole or 3-amino-5-methylthio-1H-1,2,4-triazole.

[0009] The copper surface micro-etching ultra-roughening liquid of the present invention adopts a specific micro-etching system combined with a specific azole corrosion inhibitor, thereby achieving selective corrosion of the copper surface, increasing the roughness of the copper surface, forming a more rugged morphology, which is beneficial to increase the contact area and enhance the interface bonding strength between copper and resin.

[0010] Preferably, the azole corrosion inhibitor is selected from 3-amino-5-methylthio-1H-1,2,4-triazole and / or 3,5-diamino-1,2,4-triazole.

[0011] Preferably, the concentration of the azole corrosion inhibitor is 280-320 ppm.

[0012] In some embodiments, the pH value of the copper surface micro-etching and super-roughening solution is 3-4.

[0013] In some embodiments, the concentration of the solute is: copper ion 0.2-0.4 mol / L, chloride ion 0.3-0.8 mol / L, organic acid 0.15-0.4 mol / L, organic acid salt 1-2 mol / L.

[0014] Optionally, the concentration of copper ions that can achieve the purpose of the present invention can be 0.2mol / L, 0.22mol / L, 0.24mol / L, 0.26mol / L, 0.28mol / L, 0.3mol / L, 0.32mol / L, 0.34mol / L, 0.36mol / L, 0.38mol / L, 0.4mol / L or any range between the above values.

[0015] Optionally, the concentration of chloride ions that can achieve the purpose of the present invention can be 0.3mol / L, 0.35mol / L, 0.4mol / L, 0.45mol / L, 0.5mol / L, 0.55mol / L, 0.6mol / L, 0.65mol / L, 0.7mol / L, 0.75mol / L, 0.8mol / L or any range between the above values.

[0016] Optionally, the concentration of the organic acid that can achieve the purpose of the present invention can be 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L or any range therebetween.

[0017] Optionally, the concentration of the organic acid salt that can achieve the purpose of the present invention can be 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2 mol / L or any range between the above values.

[0018] Optionally, the concentration of the azole corrosion inhibitor that can achieve the purpose of the present invention can be 100 ppm, 120 ppm, 140 ppm, 160 ppm, 180 ppm, 200 ppm, 220 ppm, 240 ppm, 260 ppm, 280 ppm, 300 ppm, 320 ppm, 340 ppm, 360 ppm, 380 ppm, 400 ppm or any range between the above values.

[0019] In some embodiments, the copper ions are provided by a copper ion source selected from at least one of copper chloride, copper formate, copper oxalate, copper acetate, copper citrate or copper gluconate. Preferably, the copper ion source is a combination of copper chloride and copper formate.

[0020] In some embodiments, the chloride ions are provided by a chloride ion source, and the chloride ion source is selected from at least one of sodium chloride, potassium chloride, copper chloride or ammonium chloride. Preferably, the chloride ion source is a combination of copper chloride and copper formate, or a combination of ammonium chloride and copper chloride.

[0021] In some embodiments, the organic acid is provided by an organic acid source, and the organic acid source is selected from at least one of formic acid, acetic acid, citric acid, maleic acid, acrylic acid, and gluconic acid. Preferably, the organic acid source is formic acid and / or acetic acid; more preferably, the molar ratio of formic acid to acetic acid is (0.2-5):1, preferably (2-4):1.

[0022] In some embodiments, the organic acid salt comprises an organic acid ion and a metal ion.

[0023] Optionally, the organic acid ions are selected from at least one of formate ions, acetate ions, citrate ions, maleate ions, acrylate ions or gluconate ions; preferably, the organic acid ions are formate ions and / or acetate ions.

[0024] Optionally, the metal ion is selected from at least one of sodium ion, potassium ion or copper ion; preferably, the metal ion is sodium ion.

[0025] The invention protects the application of a copper surface micro-etching and roughening liquid in the manufacture of printed circuit boards.

[0026] The present invention protects a manufacturing process of a copper-clad laminated PCB substrate, comprising the following steps: S1, spray etching the copper foil with a copper surface micro-etching roughening liquid to obtain a roughened copper foil; S2, laminating and thermally curing the roughened copper foil and thermosetting resin to obtain the copper-clad laminated PCB substrate.

[0027] In some of the embodiments, in step S1, the temperature of the spray etching is 25-40° C., the spray frequency is 40-100 times / min, the spray pressure is 4-8 Bar, and the spray time is 60-300 s.

[0028] In some embodiments, in step S1, the surface roughness Rpv of the roughened copper foil is 1.8-3.5 μm.

[0029] In some embodiments, in step S2, the lamination temperature is 100-120°C, preferably 108-112°C; the pressure is 7-12 kgf / cm 2 , preferably 8-9kgf / cm 2 Preferably, the lamination is processed in a vacuum environment, or in a near-vacuum environment with a vacuum degree of more than 0.7 MPa.

[0030] The present invention has no particular limitation on the thermosetting resin, and conventional resins in the field of PCB substrates may be used; optionally, the thermosetting resin is selected from any one of epoxy resin, polyimide resin, bismaleimide triazine resin, phenolic resin, cyanate resin or polytetrafluoroethylene; preferably, the epoxy resin is specifically ABF resin.

[0031] In some embodiments, in step S2, when the thermosetting resin is an epoxy resin, the temperature of the thermal curing is 160-200° C., preferably 175-185° C.; the thermal curing time is 90-150 min, preferably 115-125 min.

[0032] Compared with the prior art, the present invention has the following beneficial effects: The invention provides a copper surface micro-etching ultra-roughening liquid, which adopts a specific micro-etching system combined with a specific azole corrosion inhibitor to achieve selective corrosion of the copper surface and form a more rugged morphology, which is beneficial to increase the contact area and enhance the interface bonding strength between copper and resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a diagram showing the pull-off test results of the substrate after the copper surface is treated with the ultra-roughening solution according to Example 1 of the present invention.

[0034] Figure 2 This is a diagram showing the pull-off test results of the substrate after the copper surface is treated with an ultra-roughening solution according to Example 2 of the present invention.

[0035] Figure 3 This is a diagram showing the pull-off test results of the substrate after the copper surface is treated with an ultra-roughening solution according to Example 3 of the present invention.

[0036] Figure 4 This is a diagram showing the pull-off test results of the substrate after the copper surface is treated with an ultra-roughening solution according to Example 4 of the present invention.

[0037] Figure 5 This is a diagram showing the pull-off test results of the substrate after the copper surface was treated with an ultra-roughening solution according to Example 5 of the present invention.

[0038] Figure 6 This is a diagram showing the pull-off test results of the substrate after the copper surface is treated with an ultra-roughening solution in Comparative Example 1 of the present invention.

[0039] Figure 7 This is a diagram showing the pull-off test results of the substrate after the copper surface is treated with an ultra-roughening solution according to Comparative Example 2 of the present invention.

[0040] Figure 8 This is a SEM image of the roughened copper foil after being treated with the copper surface micro-etching super-roughening solution according to Example 1 of the present invention.

[0041] Fig. 9 This is a SEM image of the roughened copper foil after being treated with the copper surface micro-etching super-roughening solution according to Example 2 of the present invention.

[0042] Fig.10 This is a SEM image of the roughened copper foil after being treated with the copper surface micro-etching super-roughening solution according to Example 3 of the present invention.

[0043] Fig.11This is a SEM image of the roughened copper foil after being treated with the copper surface micro-etching super-roughening solution according to Example 4 of the present invention.

[0044] Fig.12 This is a SEM image of the roughened copper foil after being treated with the copper surface micro-etching super-roughening solution according to Example 5 of the present invention.

[0045] Fig.13 This is a SEM image of the roughened copper foil after being treated with the copper surface micro-etching super-roughening solution in Comparative Example 1 of the present invention.

[0046] Fig.14 This is a SEM image of the roughened copper foil after being treated with a super-roughening solution for micro-etching the copper surface in Comparative Example 2 of the present invention.

[0047] Fig.15 This is a SEM image of the electroplated copper foil that has not been treated with copper surface micro-etching and super-roughening solution.

[0048] Fig.16 This is a FIB analysis diagram of the substrate after the copper surface micro-etching super-roughening solution is treated in Example 1 of the present invention.

[0049] Fig.17 This is an AFM analysis image of the roughened copper foil after being treated with the copper surface micro-etching super-roughening solution according to Example 2 of the present invention.

[0050] Fig.18 This is an AFM analysis image of the roughened copper foil after being treated with a super-roughening solution for micro-etching of the copper surface in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0051] The present invention will be further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form.

[0052] Example 1 A copper surface micro-etching and ultra-roughening solution, the solvent is water, the pH value is 3.5, and the solute includes the following components: Copper chloride 0.3 mol / L, sodium formate 1.3 mol / L, formic acid 0.2 mol / L, 3-amino-5-methylthio-1H-1,2,4-triazole 200 ppm.

[0053] The preparation method of the copper surface micro-etching and ultra-roughening solution is as follows: adding the solute component into a solvent and stirring evenly at room temperature to obtain the solution. The preparation methods of the following examples and comparative examples are the same as those of this example and will not be described in detail.

[0054] Example 2 A copper surface micro-etching and ultra-roughening solution, the solvent is water, the pH value is 3.5, and the solute includes the following components: Copper chloride 0.25 mol / L, ammonium chloride 0.15 mol / L, sodium formate 1.3 mol / L, formic acid 0.15 mol / L, acetic acid 0.05 mol / L, 3,5-diamino-1,2,4-triazole 300 ppm.

[0055] Example 3 A copper surface micro-etching and ultra-roughening solution, the solvent is water, the pH value is 3.5, and the solute includes the following components: Copper chloride 0.2 mol / L, sodium formate 1.3 mol / L, formic acid 0.2 mol / L, 1-hydroxybenzotriazole 200 ppm.

[0056] Example 4 A copper surface micro-etching and ultra-roughening solution, the solvent is water, the pH value is 3.5, and the solute includes the following components: Copper chloride 0.2 mol / L, sodium formate 1.3 mol / L, formic acid 0.2 mol / L, 2-aminobenzimidazole 400 ppm.

[0057] Example 5 A copper surface micro-etching and ultra-roughening solution, the solvent is water, the pH value is 3.5, and the solute includes the following components: Copper chloride 0.2 mol / L, sodium formate 1.3 mol / L, formic acid 0.2 mol / L, tetrazole 300 ppm.

[0058] Example 6 A copper surface micro-etching and ultra-roughening liquid, the solvent is water, and the solute includes the following components: Copper chloride 0.2 mol / L, ammonium chloride 0.2 mol / L, copper formate 0.1 mol / L, sodium formate 1.5 mol / L, formic acid 0.2 mol / L, acetic acid 0.1 mol / L, 3-amino-5-methylthio-1H-1,2,4-triazole 400 ppm.

[0059] Example 7 A copper surface micro-etching and ultra-roughening liquid, the solvent is water, and the solute includes the following components: Copper chloride 0.2 mol / L, sodium formate 1 mol / L, formic acid 0.2 mol / L, 3-amino-5-methylthio-1H-1,2,4-triazole 100 ppm.

[0060] Example 8 A manufacturing process for a copper-clad laminated PCB substrate comprises the following steps: S1, using the copper surface micro-etching roughening solution of Example 1 to spray-etch the electroplated copper foil, after etching, using a 3.5wt.% dilute hydrochloric acid aqueous solution to clean the copper surface, then washing with deionized water, and drying with nitrogen purge to obtain a roughened copper foil.

[0061] The spray etching conditions are as follows: temperature of 30° C., spray time of 300 s, spray frequency of 60 times / min, and spray pressure of 8 Bar.

[0062] S2, laminating and thermally curing the roughened copper foil and thermosetting resin to obtain the copper-clad laminated PCB substrate.

[0063] Specifically, the thermosetting resin is an epoxy resin (ABF resin, Ajinomoto, GX92). After thawing at 100°C for 60 minutes, the roughened copper foil and the epoxy resin are subjected to vacuum hot pressing. The hot pressing temperature is 110°C and the pressure is 8 kgf / cm 2 , and then timely perform thermal curing, the thermal curing temperature is 180°C; the thermal curing time is 120 minutes, and a copper-clad laminated PCB substrate is obtained.

[0064] Comparative Example 1 A copper surface micro-etching and super-roughening solution, which is different from Example 1 in that: no corrosion inhibitor is added in this comparative example; Specifically, the solvent of this comparative example is water, the pH value is 3.5, and the solute includes the following components: Copper chloride 0.3 mol / L, sodium formate 1.3 mol / L, formic acid 0.2 mol / L.

[0065] Comparative Example 2 A copper surface micro-etching and super-roughening solution, which is different from Example 1 in that: the corrosion inhibitor in this comparative example is 2-undecyl imidazoline; Specifically, the solvent of this comparative example is water, the pH value is 3.5, and the solute includes the following components: Copper chloride 0.3 mol / L, sodium formate 1.3 mol / L, formic acid 0.2 mol / L, 2-undecyl imidazoline 200 ppm.

[0066] Performance Testing The copper surface micro-etching and ultra-roughening liquid of each embodiment and comparative example was used as a sample liquid. The sample liquid was sprayed on the copper foil to obtain a roughened copper foil according to the manufacturing process of Example 8. The roughened copper foil was pressed with a resin to obtain a PCB substrate. The roughened copper foil or PCB board was subjected to the following performance tests: 1. Pull-off test: Test according to the method of IPC-TM-650 (2018) standard.

[0067] The results are as follows Figure 1-7 As shown, the maximum bonding strength of the PCB board sample treated with the roughening solution of Example 1 under 90° peeling is 15.392 kN / m ( Figure 1 ); The maximum bonding strength of the sample in Example 2 is 15.738 kN / m ( Figure 2); The maximum bonding strength of the sample in Example 3 is 14.058 kN / m ( Figure 3 ); The maximum bonding strength of the sample of Example 4 is 15.514 kN / m ( Figure 4 ); The maximum bonding strength of the sample in Example 5 is 11.296 kN / m ( Figure 5 ).

[0068] However, due to excessive corrosion of the copper surface, the maximum bonding strength of the sample in comparative example 1 is only 5.622 kN / m ( Figure 6 ), the sample of comparative example 2 has too high corrosion resistance on the metal surface, which affects the etching effect, and the bonding strength is not significantly improved. The maximum bonding strength is only 4.366 kN / m ( Figure 7 ).

[0069] Similarly, the surface roughening effect characterization and bonding strength of the copper surface micro-etching super-roughening solution of Examples 6-7 on the copper surface are equivalent to those of Example 1, and the effect characterization is not repeated here.

[0070] 2. SEM characterization SEM results are as follows Figure 8-15 As shown, the electroplated copper foil without roughening treatment is used as a blank control example ( Fig.15 ), whose surface morphology is flat; the roughened copper foil of Example 1-5 ( Figures 8 to 12 ) It can be seen that the copper surface micro-etching super-roughening liquid can selectively corrode the copper surface, protecting only a part of the surface, thereby forming a more rugged morphology on the surface, thereby increasing the contact area, which is beneficial to improving the bonding strength between copper and resin. Fig.13 ) It can be seen that the copper surface micro-etching super-roughening solution without adding corrosion inhibitor seriously corrodes the copper surface and reduces the surface roughness. Fig.14 ) Among them, the imidazoline corrosion inhibitor has too high overall anti-corrosion performance for the metal surface and the surface roughness is low.

[0071] 3. FIB Characterization like Fig.16 As shown, in the FIB analysis of the experiment in Example 1, more hook-shaped columnar structures can be seen, and the roughness Rpv can reach 3.048 μm, which significantly increases the contact area and enhances the bonding force.

[0072] 4. AFM characterization like Fig.17 As shown, in the AFM analysis of the experiment in Example 2, a columnar structure with a relatively flat top can be seen, and the columnar structure has a large height difference and a large contact area, which is beneficial to improving the copper-resin interface bonding strength.

[0073] like Fig.18As shown, in the AFM analysis of the comparative example 2 experiment, a relatively uniform peak-like structure can be seen at the top, but the overall height difference is low and the contact area is small.

[0074] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A copper surface micro-etching and ultra-roughening solution, characterized in that: Water is used as solvent, and the solutes include copper ions, chloride ions, organic acids, organic acid salts and 100-400ppm azole corrosion inhibitors; The azole corrosion inhibitor is selected from at least one of 1-hydroxybenzotriazole, 3,5-diamino-1,2,4-triazole, 2-aminobenzimidazole, tetrazole or 3-amino-5-methylthio-1H-1,2,4-triazole.

2. The copper surface micro-etching and super-roughening solution according to claim 1, characterized in that: The concentrations of the solutes are: copper ion 0.2-0.4 mol / L, chloride ion 0.3-0.8 mol / L, organic acid 0.15-0.4 mol / L, and organic acid salt 1-2 mol / L.

3. The copper surface micro-etching and super-roughening solution according to claim 1 or 2, characterized in that: The copper ions are provided by a copper ion source, and the copper ion source is selected from at least one of copper chloride, copper formate, copper oxalate, copper acetate, copper citrate or copper gluconate.

4. The copper surface micro-etching and super-roughening solution according to claim 1 or 2, characterized in that: The chloride ions are provided by a chloride ion source, and the chloride ion source is selected from at least one of sodium chloride, potassium chloride, copper chloride or ammonium chloride.

5. The copper surface micro-etching and super-roughening solution according to claim 1 or 2, characterized in that: The organic acid is provided by an organic acid source, and the organic acid source is selected from at least one of formic acid, acetic acid, citric acid, maleic acid, acrylic acid, and gluconic acid.

6. The copper surface micro-etching and super-roughening solution according to claim 1 or 2, characterized in that: The organic acid salt comprises organic acid radical ions and metal ions; The organic acid ion is selected from at least one of formate ion, acetate ion, citrate ion, maleate ion, acrylate ion or gluconate ion, The metal ions are selected from at least one of sodium ions, potassium ions or copper ions.

7. The copper surface micro-etching and super-roughening solution according to claim 1, characterized in that: The pH value of the copper surface micro-etching and super-roughening solution is 3-4.

8. Use of the copper surface micro-etching and roughening solution according to any one of claims 1 to 7 in the manufacture of printed circuit boards.

9. A manufacturing process for a copper-clad laminated PCB substrate, characterized in that: The following steps are involved: S1, spray-etching a copper foil using the copper surface micro-etching roughening solution according to any one of claims 1 to 6 to obtain a roughened copper foil; S2, laminating and thermally curing the roughened copper foil and thermosetting resin to obtain the copper-clad laminated PCB substrate.

10. The manufacturing process of the copper-clad laminated PCB substrate according to claim 9, characterized in that: In step S1, the temperature of the spray etching is 25-40°C, the spray frequency is 40-100 times / min, the spray pressure is 4-8 Bar, and the spray time is 60-300s.

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