CN110042372B - Novel use of sulfonic aromatic compounds - Google Patents

Abstract

The invention relates to a novel application of a sulfonic aromatic compound, in particular to an application of the sulfonic aromatic compound with the structure of formula (I) or a salt thereof in surface chemical copper plating of a non-metallic substrate. The non-metal substrate is treated by the pre-immersion liquid containing the sulfonic aromatic compound with the structure of the formula (I), palladium ions can be adsorbed on the substrate more uniformly after an activation step, the adsorption amount is large, and the palladium adsorption amount can be ensured even if the non-metal substrate is treated in the activation liquid with low palladium ion concentration.

Description

Novel use of sulfonic aromatic compounds

Technical Field

The invention relates to the field of chemical copper plating on the surface of a non-metal substrate, in particular to a new application of a sulfonic aromatic compound.

Background

At present, the production process of the printed circuit board generally comprises a process of metalizing the surface of a non-metal substrate (especially hole walls). Electroless copper plating is a common way of metallizing non-metallic surfaces, and the process of electroless copper plating requires the formation of a layer of active catalytic centers on the surface of a non-metallic substrate to catalyze the deposition of copper ions on the surface of the substrate. Palladium metal has been used as an active catalytic center for electroless copper plating because of its good catalytic activity and ability to improve the adhesion between the copper layer and the substrate surface. At present, the palladium catalytic system mainly comprises colloidal palladium and ionic palladium. Compared with a colloid palladium activation system, the ionic palladium system has better stability, but palladium ions in the ionic palladium have poor adhesive force on a non-metal substrate and are easy to be unevenly distributed, so that the subsequent electroless copper plating is caused to generate plating leakage. If the concentration of palladium ions in the activating solution needs to be increased in order to ensure that the palladium ions can completely cover the surface of the substrate, the consumption of the noble metal palladium is excessive, and the cost is high.

In order to solve the problems of incomplete coverage and poor adhesion of palladium ions, technicians perform pre-dipping before activation, but the prior pre-dipping solution still has the following problems: the ability of adjusting the surface charge of the substrate is still insufficient, so that the problems of low and uneven adsorption of palladium ions on the surface of the substrate still exist in the subsequent activation step, the consumption of palladium is still increased, and the problem of high cost is caused.

Disclosure of Invention

Based on the above, the invention provides an application of sulfonic aromatic compound or its salt in surface electroless copper plating of a non-metal substrate, wherein the non-metal substrate is treated by using a pre-immersion liquid containing the sulfonic aromatic compound having the structure of formula (I), and after an activation step, palladium ions can be adsorbed on the substrate more uniformly and in a large amount, and the palladium adsorption amount can be ensured even if the non-metal substrate is treated in an activation liquid with a low palladium ion concentration.

The specific technical scheme is as follows:

the application of sulfonic aromatic compound or salt thereof with the structure of formula (I) in chemical copper plating on the surface of a non-metallic substrate;

wherein R is₁Is substituted or unsubstituted C8-C14 alkyl;

R₂selected from oxy, C1-C4 alkyl, -R₃OR₄—；

R₃And R₄Each independently selected from C1-C2 alkyl.

In one embodiment, R is₁Is hydroxyl or halogen substituted C8-C14 alkyl.

In one embodiment, R is₁Is 2-chlorododecyl, 2-methyldecyl, n-tetradecyl, 3-ethyloctyl, 1-hydroxyoctyl or n-octyl;

R₂selected from the group consisting of oxy, methylene, isopropyl, 1, 4-butylene, — R₃OR₄—。

In one embodiment, the non-metallic substrate is selected from a resin, a mixture of a resin and glass fibers.

The invention also provides a pre-immersion liquid.

The specific technical scheme is as follows:

a pre-immersion liquid, the raw material of which comprises a compound having the structure of formula (I) or a salt thereof;

wherein R is₁Is substituted or unsubstituted C8-C14 alkyl;

R₂selected from oxy, C1-C4 alkyl, -R₃OR₄—；

R₃And R₄Each independently selected from C1-C2 alkyl.

In one embodiment, R is₁Is hydroxyl or halogen substituted C8-C14 alkyl.

In one embodiment, R is₁Is 2-chlorododecyl, 2-methyldecyl, n-tetradecyl, 3-ethyloctyl, 1-hydroxyoctyl or n-octyl;

R₂selected from the group consisting of oxy, methylene, isopropyl, 1, 4-butylene, — R₃OR₄—。

In one embodiment, the pre-dip comprises a solvent and the following concentrations of the raw materials:

the compound with the structure of the formula (I) or the salt thereof is 20mg/L-150 mg/L;

40mg/L-275mg/L of dispersant;

and a proper amount of pH regulator.

In one embodiment, the dispersant is selected from one or more of polyvinylpyrrolidone, polyacrylamide, polymaleic anhydride, polyethylene glycol, polyethylene oxide, and hydroxyethyl cellulose.

In one embodiment, the pre-dip has a pH of 1-4.

In one embodiment, the pH adjusting agent is selected from one or more of sulfuric acid, phosphoric acid, formic acid, acetic acid, or a hydrogenated salt thereof.

The invention also provides a method for chemically plating copper on the surface of the non-metallic substrate.

The specific technical scheme is as follows:

a method for chemically plating copper on the surface of a non-metallic substrate comprises the following steps:

immersing a non-metal substrate in the pre-immersion liquid for pre-immersion;

immersing the pre-soaked non-metal substrate in an activating solution for activation;

and immersing the activated non-metal substrate in a copper plating solution to carry out chemical copper plating, thus obtaining the copper-plated non-metal substrate.

The principle and advantages of the invention are as follows:

at present, the sulfonic aromatic compound with the structure of formula (I) is more used for oil exploitation, and the inventor of the invention finds that the compound with the structure is used in non-metal surface chemical plating, particularly, the sulfonic aromatic compound with the structure of formula (I) is added into a pre-immersion liquid for chemical copper plating of a non-metal substrate, the non-metal substrate is treated by the pre-immersion liquid, palladium ions can be adsorbed on the substrate more uniformly after an activation step, the adsorption amount is larger, and the palladium adsorption amount can be ensured even if the treatment is carried out in an activation liquid with lower palladium ion concentration.

The possible mechanism is:

the sulfonic aromatic compound with the structure can form an organic covering film of an electric double layer on the surface of the substrate, at the moment, the aromatic ring structure faces to the solution side, and the sulfonic aromatic compound and the complex of the alkaline ionic palladium generate stronger bonding action, so that palladium ions in the subsequent activation step are more efficiently adsorbed, the concentration of the palladium ions in the activation solution is reduced on the premise of ensuring the activation effect, and the process cost is greatly reduced.

Drawings

FIG. 1 is a backlight effect picture of an electroless copper plated part of example 1;

fig. 2 is a backlight effect picture of the electroless copper plated article of comparative example 1.

Detailed Description

The novel use of the sulfonic acid group aromatic compound of the present invention will be described in further detail with reference to specific examples. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In the following detailed description, unless otherwise specified, all conventional methods are used; the raw materials, reagents, and the like used in the following embodiments are all commercially available products unless otherwise specified.

The sulfonic aromatic compound can be purchased from Sigma-Aldrich company (Sigma Aldrich company) or prepared by referring to the prior published documents, such as Scheiwei, etc., the synthesis and surface properties of 4-alkyl diphenyl methane disulfonate, 2014, Lijun, the synthesis of hexadecyl diphenyl ether disulfonate and the application research thereof in tertiary oil recovery, 2010, etc.

The dispersant of the invention has the function of enabling the pre-immersion liquid to fully infiltrate the surface of the substrate, especially the surface of the hole wall, so that palladium ions can be more uniformly attached to the substrate in the subsequent activation step. The dispersant is generally a polymer, and may be an anionic, cationic or nonionic high molecular polymer, such as PEG 2000-6000.

The non-metal substrate resin can be epoxy resin, or common resins such as amino resin, polyester resin, phenolic resin, acrylic resin, polysiloxane, polyamide, polyimide, diallyl phthalate, phenyl silane, polybenzimidazole, diphenyl ether, polytetrafluoroethylene, cyanate ester and the like.

The pre-immersion liquid can be prepared according to a conventional method, and the method comprises the following steps: setting the total volume to be 2L according to the concentration of each component, calculating the mass of each component, then weighing each component, respectively dissolving each component in a certain amount of water, uniformly mixing and stirring, and then fixing the volume to be 2L for later use.

The conventional chemical plating process mainly comprises the following steps: swelling, removing glue, neutralizing, removing oil, micro-etching and presoaking, immersing the substrate in an activating solution for activation after presoaking, reducing the activated metal ions on the surface of the substrate, and finally immersing the substrate in a chemical plating metal solution for depositing target metal. The treatment before activation may be carried out according to the following main procedures, between each of which there may be a step of washing with water:

(1) expansion: swelling the substrate at 70 ℃ by using 50% of isoamylol, 10% of sodium hydroxide and 40% of water, and treating for 2 minutes;

(2) removing glue: oxidizing and removing resin swelled in the pores by adopting potassium permanganate under an alkaline condition at 75 ℃, and treating for 3 minutes;

(3) neutralizing: at room temperature, oxalic acid is adopted to neutralize and reduce residual potassium permanganate and the like for 40 seconds;

(4) oil removal: removing oil stains on the surface of the substrate at 45 ℃ by adopting a mixed solution of 5% of sodium hydroxide, 6% of sodium carbonate and 89% of water, and treating for 1 minute;

(5) micro-etching: treating for 1 minute at room temperature with a mixture of 30% sulfuric acid, 15% sodium persulfate and 55% water;

(6) pre-dipping: immersing the glass fiber in the pre-immersion liquid for 25 to 40 seconds;

(7) and (3) activation: immersing the substrate in an activating solution containing 50ppm (calculated according to the concentration of palladium ions) of palladium chloride, 0.3g/L of alpha-aminopyridine and having a pH value of 8-12, and treating for 60 seconds;

(8) reduction: reducing by treating with 0.1% sodium borohydride aqueous solution for 40 seconds;

(9) chemical copper plating: immersing in chemical copper plating solution containing 16g/L copper sulfate, 10g/L potassium sodium tartrate, 15g/L LEDTA disodium salt, 15mg/L formaldehyde and 13g/L sodium hydroxide, and treating for 5 minutes to complete copper plating.

Examples 1 to 6

A pre-dip was prepared from the components and their concentrations as described in table 1. The preparation method comprises the following steps:

setting the total volume to be 2L, calculating the mass of each component, then weighing each component, respectively dissolving each component in a certain amount of water, mixing and stirring uniformly, and then fixing the volume to be 2L for later use.

TABLE 1

Wherein the methylene has the structure

Comparative examples 1 to 3

A pre-dip was prepared by the same preparation method as in example 1, based on the components and their concentrations shown in table 2.

TABLE 2

Performance testing

And (3) comparing the backlight grade of electroless copper plating:

according to the electroless plating process described above, electroless copper plating was performed using FR-4 resin (containing glass fiber) as a base material, and in the case of the prepreg, the same electroless plating process was performed using the prepreg obtained in each of examples 1 to 6 and comparative examples 1 to 3. And after the electroless copper plating is finished, observing the backlight effect and the backlight grade of each plated part.

Among them, the backlight effect of the electroless copper plated article of example 1 is shown in fig. 1, and the backlight effect of the electroless copper plated article of comparative example 1 is shown in fig. 2. The results of the backlight ratings of the plated articles corresponding to examples 1 to 6 and comparative examples 1 to 3 are shown in table 3.

TABLE 3

Pre-immersion liquid	Backlight grade
		Example 1	Grade 10
Example 2	Grade 9.5
		Example 3	Grade 9
Example 4	Grade 10
		Example 5	Grade 10
Example 6	Grade 9
		Comparative example 1	Stage 8
Comparative example 2	7.5 grade
		Comparative example 3	Stage 7

Analysis of results

From the above results, it can be seen that after the treatment of the pre-immersion liquids of examples 1-6, even if the subsequent activation is carried out in the activating solution with relatively low palladium ion concentration (50ppm), the final backlight grade of electroless copper plating can be ensured to be above grade 9, and the backlight effect requirement of electroless copper plating in the industry can be met.

Comparative examples 1 to 3 are comparative experiments of the pre-immersion liquids of examples 1 to 3, respectively, after the pre-immersion liquids of comparative examples 1 to 3 are treated, the pre-immersion liquids are also activated in an activating solution with relatively low palladium ion concentration (50ppm), and the final backlight grade of the electroless copper plating reaches 8 grades at most, which does not meet the requirements of backlight grade in the industry.

Furthermore, as can be seen from fig. 1 and fig. 2, compared to example 1, the black region in the middle of comparative example 1 has a light transmission phenomenon, and a small amount of light spots appear, which indicates that the backlight effect of example 1 is better, and further verifies that the backlight grade of example 1 is higher.

Therefore, the sulfonic aromatic compound with the structure shown in the formula (I) is used in the pre-immersion liquid for electroless copper plating, compared with the method that a common surfactant is added into the pre-immersion liquid, the adsorption amount of palladium ions during subsequent activation can be obviously improved, the backlight grade of the subsequent electroless copper plating can be ensured even if the treatment is carried out in the activation liquid with relatively low palladium ion concentration, and the quality of a plated part is ensured.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. The application of sulfonic aromatic compound or salt thereof with the structure of formula (I) in chemical copper plating on the surface of a non-metallic substrate;

formula (I)

Wherein R is₁Is substituted or unsubstituted C8-C14 alkyl;

R₂selected from oxy, C1-C4 alkyl, -R₃OR₄—；

R₃And R₄Each independently selected from C1-C2 alkyl.

2. Use according to claim 1, wherein R is₁Is hydroxyl or halogen substituted C8-C14 alkyl.

3. Use according to claim 2, wherein R is₁Is 2-chlorododecyl, 2-methyldecyl, n-tetradecyl, 3-ethyloctyl, 1-hydroxyoctyl or n-octyl;

R₂selected from the group consisting of oxy, methylene, isopropyl, 1, 4-butylene, — R₃OR₄—。

4. Use according to any one of claims 1 to 3, wherein the non-metallic substrate is selected from the group consisting of resins, mixtures of resins and glass fibres.

5. A pre-dip for electroless copper plating, characterized in that the raw materials thereof comprise a compound having the structure of formula (I) or a salt thereof;

formula (I)

Wherein R is₁Is substituted or unsubstituted C8-C14 alkyl;

R₂selected from oxy, C1-C4 alkyl, -R₃OR₄—；

R₃And R₄Each independently selected from C1-C2 alkyl.

6. The pre-dip according to claim 5, characterized in that it comprises a solvent and the following concentrations of raw materials:

the compound with the structure of the formula (I) or the salt thereof is 20mg/L-150 mg/L;

40mg/L-275mg/L of dispersant;

and a proper amount of pH regulator.

7. The pre-dip according to claim 6, wherein the dispersing agent is selected from one or more of polyvinylpyrrolidone, polyacrylamide, polymaleic anhydride, polyethylene glycol, polyethylene oxide and hydroxyethyl cellulose.

8. The pre-dip according to claim 6, wherein the pre-dip has a pH value of 1-4.

9. The pre-dip according to claim 8, wherein the pH adjusting agent is selected from one or more of sulfuric acid, phosphoric acid, formic acid, acetic acid, or a hydrogenated salt thereof.

10. A method for chemically plating copper on the surface of a non-metal substrate is characterized by comprising the following steps:

immersing a non-metallic substrate in the pre-immersion liquid according to any one of claims 5 to 9 to perform pre-immersion;

immersing the pre-soaked non-metal substrate in an activating solution for activation;

and immersing the activated non-metal substrate in a copper plating solution to carry out chemical copper plating, thus obtaining the copper-plated non-metal substrate.

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