CN118563296A - Post-electroless nickel plating dip and preparation method and application thereof - Google Patents

Abstract

The present invention discloses a chemical nickel plating post-immersion agent and a preparation method and application thereof, and relates to the field of chemical nickel plating auxiliary agents. Wherein, the chemical nickel plating post-immersion agent includes sulfuric acid, a palladium adsorbent and deionized water, the mass concentration of the sulfuric acid is 10-20 g/L, and the mass concentration of the palladium adsorbent is 4-5 g/L; wherein, the palladium adsorbent is a product of polymerization of acrylamide or maleic acid and a cationic quaternary ammonium salt monomer. The post-immersion agent of the present application can effectively remove Pd2 ⁺ which is difficult to remove within the small line width and line spacing of an IC carrier, solve the problem that the IC carrier is easy to penetrate gold, and improve the product yield.

Description

Chemical nickel plating post-immersion agent and its preparation method and application

Technical Field

The present application relates to the field of chemical nickel plating additives, and in particular to a chemical nickel plating post-immersion agent and a preparation method and application thereof.

Background Art

The traditional chemical nickel-palladium-gold plating process is as follows: degreasing-microetching-pickling-pre-immersion-activation-post-immersion-chemical nickel-chemical palladium-chemical gold. In the post-immersion step, a sulfuric acid solution with a mass concentration of 2-3% is usually used as a post-immersion agent.

However, as electronic products develop towards high frequency and high speed, the design of IC substrates is also increasingly tending towards high frequency, high speed, high density and miniaturization. This dense and complex circuit working environment has brought new challenges to the stability and reliability of the surface treatment process of printed circuit boards. Among them, for IC substrates with small line width and line spacing, especially IC substrates with line width and line spacing below 20μm, using traditional sulfuric acid solution with a mass concentration of 2-3% as a post-immersion agent is likely to lead to poor gold penetration, resulting in a large number of scrapped products.

Summary of the invention

In order to improve the problem in the related art that when sulfuric acid solution is used as a post-immersion agent for IC substrates with a line width and line spacing of less than 20 μm, the solution causes poor gold penetration, the present application provides a chemical nickel plating post-immersion agent and a preparation method and application thereof.

In the first aspect, the present application provides a chemical nickel plating post-immersion agent using the following technical solution:

A post-immersion agent for chemical nickel plating comprises sulfuric acid, a palladium adsorbent and deionized water, wherein the mass concentration of the sulfuric acid is 10-20 g/L, and the mass concentration of the palladium adsorbent is 4-5 g/L; wherein the palladium adsorbent is a product of polymerization of acrylamide or maleic acid and a cationic quaternary ammonium salt monomer.

In the present application, the post-chemical nickel plating immersion agent includes sulfuric acid and a palladium adsorbent. The sulfuric acid can quickly clean the Pd ²⁺ on the surface of the IC substrate. The palladium adsorbent has excellent penetration and can smoothly enter and exit the tiny line width and line spacing of the IC substrate with a size of less than 20 μm, and adsorb the Pd ²⁺ remaining in the tiny line width and line spacing of the IC substrate after the activation step. At the same time, under the action of sulfuric acid, the palladium adsorbent is easily removed by water washing without introducing new residues into the IC substrate, which is beneficial to prevent gold penetration problems caused by Pd ²⁺ residues on the IC substrate, and can also prevent other product quality problems caused by the residues of the palladium adsorbent.

In addition, compared with the use of palladium adsorbent alone as a post-immersion agent, the combination of sulfuric acid and palladium adsorbent can effectively remove the Pd ²⁺ that is difficult to remove within the small line width and line spacing of the IC substrate, solve the problem of easy gold penetration of the IC substrate, and improve the product yield. At the same time, it can also reduce the cost of the chemical nickel-palladium-gold plating process, without causing the residue of palladium adsorbent, and has more economic and practical value.

Optionally, the cationic quaternary ammonium salt monomer is at least one of dimethyldiallylammonium chloride and (4-ethoxy-2-hydroxy-4-oxobut-2-enyl)trimethylammonium chloride.

Preferably, the cationic quaternary ammonium salt monomer is dimethyldiallylammonium chloride.

In the present application, when dimethyldiallyl ammonium chloride is used as the cationic monomer, the adsorption stability of the palladium adsorbent to Pd2 ⁺ is better, and the Pd2 ⁺ encapsulated in the palladium adsorbent is not easily transferred back to the post-infusion agent. After obvious solid suspended matter appears in the post-infusion agent, the solid suspended matter can be removed by filtration and then recycled. If necessary, palladium adsorbent can be added. There is no need to frequently replace the post-infusion agent in the tank, which is conducive to further reducing costs.

Preferably, the molar ratio of acrylamide or maleic acid to dimethyldiallylammonium chloride is 1:(1-3).

In the present application, when the molar ratio of acrylamide or maleic acid to dimethyldiallylammonium chloride is controlled within the range of 1:(1-3), the penetration effect of the palladium adsorbent and the adsorption effect of Pd ²⁺ are stronger, which can not only further quickly remove the Pd ²⁺ remaining in the small line width and line spacing of the IC carrier, but also the Pd ²⁺ encapsulated in the palladium adsorbent is not easy to be transferred back to the post-immersion agent. After obvious solid suspended matter appears in the post-immersion agent, the solid suspended matter can be removed by filtration and then recycled. If necessary, palladium adsorbent can be added. There is no need to frequently replace the post-immersion agent in the tank, which is conducive to further reducing costs.

More preferably, the molar ratio of acrylamide or maleic acid to dimethyldiallylammonium chloride is 1:2.

Preferably, the preparation method of the palladium adsorbent is as follows:

Mix acrylamide or maleic acid with cationic quaternary ammonium salt monomer, and then adjust the pH to 7.

The obtained product is obtained by adding ammonium persulfate-sodium bisulfite redox initiator to initiate polymerization.

In the present application, the above scheme can be used to produce a palladium adsorbent with excellent penetration, which can smoothly enter and exit the tiny line width and line spacing of less than 20 μm on the IC substrate and adsorb Pd ²⁺ remaining in the tiny line width and line spacing after the activation step.

Preferably, during the polymerization process, the reaction temperature is controlled at 75-80° C., and the reaction time is controlled at 20-30 h.

In the present application, when the reaction temperature is controlled within 75-80°C, it is not easy to cause raw material explosion, which is beneficial to improving production safety.

Optionally, in the ammonium persulfate-sodium bisulfite redox initiator, the weight ratio of ammonium persulfate to sodium bisulfite is (1.5-2):1.

In the second aspect, the present application provides a method for preparing a chemical nickel plating post-immersion agent using the following technical solution:

A method for preparing a chemical nickel plating post-immersion agent comprises the following steps:

Slowly add sulfuric acid to deionized water, stir evenly, cool to 20-35° C., then add palladium adsorbent, stir evenly, and obtain a post-immersion agent.

In the present application, sulfuric acid is first dissolved in water and cooled before adding the palladium adsorbent, which can prevent the palladium adsorbent from decomposing due to excessive temperature and affecting the removal effect of the post-immersion agent on the Pd2 ⁺ remaining in the tiny line width and line spacing of less than 20μm on the IC substrate.

In a third aspect, the application of a chemical nickel plating post-immersion agent provided by the present application adopts the following technical solution:

The invention discloses an application of a chemical nickel plating post-immersion agent, which is used in the post-immersion step of a chemical nickel palladium gold plating process.

In the present application, the above-mentioned chemical nickel plating post-immersion agent is used after the activation step of the chemical nickel palladium gold plating process and before the chemical nickel plating step to remove the residual Pd ²⁺ on the IC substrate, and the post-immersion agent can also have an excellent removal effect on the residual Pd ²⁺ within the tiny line width and line spacing of less than 20μm, which can prevent the gold penetration problem caused by the residual Pd ²⁺ on the IC substrate.

Preferably, the temperature of the post-immersion agent in the post-immersion step is controlled at 15-35° C., and the immersion time is 1-5 min, preferably 2-3 min.

In the present application, the post-immersion step can be carried out at room temperature, with a short post-immersion time and low energy consumption.

In summary, the technical solution of the present application has the following beneficial effects:

(1) In the present application, the post-chemical nickel plating immersion agent includes sulfuric acid and a palladium adsorbent. The sulfuric acid can quickly clean the Pd2 ⁺ on the surface of the IC substrate. The palladium adsorbent has excellent penetration and can smoothly enter and exit the tiny line width and line spacing of the IC substrate with a size of less than 20 μm, and adsorb the Pd2 ⁺ remaining in the tiny line width and line spacing of the IC substrate after the activation step. At the same time, under the action of sulfuric acid, the palladium adsorbent is easily removed by water washing without introducing new residues into the IC substrate, which is beneficial to preventing the gold penetration problem caused by the Pd2 ⁺ residue on the IC substrate, and also preventing the residue of the palladium adsorbent from causing other product quality problems.

In addition, compared with the use of palladium adsorbent alone as a post-immersion agent, the combination of sulfuric acid and palladium adsorbent can effectively remove the Pd ²⁺ that is difficult to remove within the small line width and line spacing of the IC substrate, solve the problem of easy gold penetration of the IC substrate, and improve the product yield. At the same time, it can also reduce the cost of the chemical nickel-palladium-gold plating process, without causing the residue of palladium adsorbent, and has more economic and practical value.

(2) In the present application, when dimethyldiallylammonium chloride is used as the cationic monomer, the adsorption stability of the palladium adsorbent to Pd2 ⁺ is better, and the Pd2 ⁺ encapsulated in the palladium adsorbent is not easy to be transferred back to the post-immersion agent. After obvious solid suspended matter appears in the post-immersion agent, the solid suspended matter can be removed by filtration and then recycled. When necessary, palladium adsorbent can be added. There is no need to frequently replace the post-immersion agent in the tank, which is conducive to further reducing costs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a product picture of an IC substrate with a line width and line spacing of less than 10-20 μm and no gold penetration.

FIG. 2 is a product picture of an IC substrate with a line width and line spacing of less than 10-20 μm when gold penetration occurs.

DETAILED DESCRIPTION

The present application is further described below based on specific experiments.

Example

[Example 1]

A post-leaching agent comprises sulfuric acid, a palladium adsorbent and deionized water, wherein the mass concentration of the sulfuric acid is 15 g/L, and the mass concentration of the palladium adsorbent is 4.5 g/L.

The preparation method of the post-infusion comprises the following steps:

Weigh 7.1 kg of acrylamide, 30 L of dimethyldiallylammonium chloride (density 0.719 g/mL), and 50 L of water in a reaction container, adjust pH to 7 with aqueous ammonia, heat the contents of the reaction container to 50° C., connect a nitrogen protection device, add 0.15 kg of an aqueous solution of ammonium persulfate having a mass concentration of 1% and 0.15 kg of an aqueous solution of sodium bisulfite having a mass concentration of 0.5%, add the mixture within 5 minutes, then raise the temperature to 75° C., react for 30 hours, and discharge the mixture to obtain a palladium adsorbent;

Sulfuric acid was slowly added to deionized water, and after being stirred evenly, the mixture was cooled to 20° C., and then a palladium adsorbent was added, and the mixture was stirred evenly to obtain a post-immersion agent.

[Example 2]

A post-leaching agent comprises sulfuric acid, a palladium adsorbent and deionized water, wherein the mass concentration of the sulfuric acid is 15 g/L, and the mass concentration of the palladium adsorbent is 4.5 g/L.

The preparation method of the post-infusion comprises the following steps:

Weigh 11.6 kg of maleic acid, 60 L of dimethyldiallylammonium chloride (density 0.719 g/mL), and 50 L of water in a reaction container, adjust the pH to 7 with aqueous ammonia, heat the materials in the reaction container to 50° C., connect a nitrogen protection device, add 0.15 kg of an aqueous solution of ammonium persulfate having a mass concentration of 1% and 0.15 kg of an aqueous solution of sodium bisulfite having a mass concentration of 0.5%, add the mixture within 5 minutes, then raise the temperature to 80° C., react for 25 hours, and discharge the mixture to obtain a palladium adsorbent;

Sulfuric acid was slowly added to deionized water, and after being stirred evenly, the mixture was cooled to 20° C., and then a palladium adsorbent was added, and the mixture was stirred evenly to obtain a post-immersion agent.

[Example 3]

A post-infusion agent, which differs from Example 1 in that dimethyldiallylammonium chloride is replaced by an equimolar amount of (4-ethoxy-2-hydroxy-4-oxobut-2-enyl)trimethylammonium chloride.

[Example 4]

A post-infusion agent, which differs from Example 2 in that dimethyldiallylammonium chloride is replaced by an equimolar amount of (4-ethoxy-2-hydroxy-4-oxobut-2-enyl)trimethylammonium chloride.

Comparative Example

[Comparative Example 1]

A post-infusion agent, which differs from [Example 1] in that dimethyldiallylammonium chloride is replaced by an equimolar amount of acrylamide.

[Comparative Example 2]

A post-infusion agent, which differs from Example 2 in that dimethyldiallylammonium chloride is replaced by maleic acid in an equal molar amount.

[Comparative Example 3]

A post-immersion agent, which differs from [Example 1] in that acrylamide is replaced by an equimolar amount of dimethyldiallylammonium chloride.

Application Examples

【Application Example 1】

The chemical nickel-palladium-gold plating process for IC substrates includes the following steps:

Step (1) sandblasting: sandblasting the IC substrate;

Step (2) Degreasing: Clean the printed circuit board with S-31 acidic degreasing agent for 5 minutes, and then wash with water;

Step (3) micro-etching: immerse the IC substrate treated in step (2) in a micro-etching solution for 2 minutes, and then wash with water; wherein the concentration of sodium persulfate in the micro-etching solution is 100 g/L, and the concentration of sulfuric acid is 50 g/L;

Step (4) acid washing: immerse the IC substrate treated in step (3) in a 100 g/L sulfuric acid solution for 3 min, and then wash with water;

Step (5) acid pre-immersion: immerse the IC substrate treated in step (4) in a 50 g/L sulfuric acid solution for 2 min;

Step (6) Activation: The IC substrate immersed in step (5) is immersed in a S-32 activator solution for activation for 5 minutes, and then washed with water;

Step (7) post-immersion: immerse the IC substrate treated in step (6) in the post-immersion agent prepared in Example 1 of the present application, the temperature of the post-immersion agent is 20° C., immerse for 2 minutes, and then wash with water;

Step (8) chemical nickel deposition: immerse the IC substrate treated in step (7) in SEN-4 chemical nickel solution, deposit nickel for 20 minutes at a temperature of 80° C., and then wash with water;

Step (9) chemical palladium deposition: the IC substrate treated in step (8) is immersed in Smet SPD-38 chemical palladium plating solution to deposit palladium. The palladium deposition time is 10 minutes and the palladium deposition temperature is 50°C.

Step (10) chemical gold plating: immerse the IC substrate treated in step (9) in a reduced chemical gold plating solution of Smet SKG-22, with a gold plating time of 20 minutes and a temperature of 80° C. to obtain an IC substrate with chemical nickel-palladium-gold plating.

【Application Example 2】

The chemical nickel-palladium-gold plating process of the IC substrate is different from that of [Application Example 1] in that the post-immersion agent in step (7) adopts the post-immersion agent prepared in [Example 2].

【Application Example 3】

The chemical nickel-palladium-gold plating process of the IC substrate is different from that of [Application Example 1] in that the post-immersion agent in step (7) adopts the post-immersion agent prepared in [Example 3].

【Application example 4】

The chemical nickel-palladium-gold plating process of the IC substrate is different from that of [Application Example 1] in that the post-immersion agent in step (7) adopts the post-immersion agent prepared in [Example 4].

Comparative Application Examples

【Comparative Application Example 1】

The chemical nickel-palladium-gold plating process of the IC substrate is different from that of [Application Example 1] in that the post-immersion agent in step (7) adopts the post-immersion agent prepared in [Comparative Example 1].

【Comparative Application Example 2】

The chemical nickel-palladium-gold plating process of the IC substrate is different from that of [Application Example 1] in that the post-immersion agent in step (7) adopts the post-immersion agent prepared in [Comparative Example 2].

【Comparative Application Example 3】

The chemical nickel-palladium-gold plating process of the IC substrate is different from that of [Application Example 1] in that the post-immersion agent in step (7) adopts the post-immersion agent prepared in [Comparative Example 3].

【Comparative Application Example 4】

The difference between the chemical nickel-palladium-gold plating process of the IC substrate and [Application Example 1] is that the post-immersion agent in step (7) is replaced by a sulfuric acid solution with a mass concentration of 1%.

Performance testing gold penetration: According to the chemical nickel-palladium-gold plating process in each application example and comparative application example, IC substrates with different line spacing and line widths are plated with nickel-palladium-gold, and it is recorded whether the finished IC substrates with different line spacing and line widths have gold penetration problems.

Table 1

Combining Application Example 1 with Comparative Application Example 1, it can be seen that in Comparative Application Example 1, the palladium adsorbent uses a polymer of acrylamide, and in Application Example 1, the palladium adsorbent uses a polymer of acrylamide and dimethyldiallylammonium chloride. Combining the data in Table 1, it can be seen that when the palladium adsorbent uses a polymer of acrylamide, it is not conducive to solving the problem of easy gold penetration of IC substrates with a line width and line spacing less than 20μm.

Combining Application Example 2 with Comparative Application Example 2, it can be seen that in Comparative Application Example 2, the palladium adsorbent uses a polymer of maleic acid, and in Application Example 2, the palladium adsorbent uses a polymer of maleic acid and dimethyldiallylammonium chloride. Combining the data in Table 1, it can be seen that when the palladium adsorbent uses a polymer of maleic acid, it is not conducive to solving the problem of easy gold penetration of IC substrates with a line width and line spacing of less than 20μm.

Combining Application Examples 1-2 with Comparative Application Example 3, it can be seen that in Comparative Application Example 3, the palladium adsorbent uses a polymer of dimethyldiallyl ammonium chloride, in Application Example 1, the palladium adsorbent uses a polymer of acrylamide and dimethyldiallyl ammonium chloride, and in Application Example 2, the palladium adsorbent uses a polymer of maleic acid and dimethyldiallyl ammonium chloride. Combining the data in Table 1, it can be seen that when the palladium adsorbent uses a polymer of dimethyldiallyl ammonium chloride, it is not conducive to solving the problem of easy gold penetration of IC carriers with a line width and line spacing less than 20μm.

Combined with Application Examples 1-4, it can be seen that when the palladium adsorbent is a product of polymerization of acrylamide or maleic acid and cationic quaternary ammonium salt monomers, it can effectively remove Pd ²⁺ that is difficult to remove within the small line width and line spacing of the IC substrate, solve the problem of easy gold penetration of the IC substrate, and improve product yield.

This specific implementation manner is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the specific implementation manner as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims (10)

1. An electroless nickel post-dip, characterized in that: the method comprises sulfuric acid, a palladium adsorbent and deionized water, wherein the mass concentration of the sulfuric acid is 10-20g/L, and the mass concentration of the palladium adsorbent is 4-5g/L; wherein the palladium adsorbent is a product of polymerization of acrylamide or maleic acid and a cationic quaternary ammonium salt monomer.

2. An electroless nickel post dip according to claim 1, wherein: the cationic quaternary ammonium salt monomer adopts at least one of dimethyl diallyl ammonium chloride and (4-ethoxy-2-hydroxy-4-oxo-but-2-alkenyl) trimethyl ammonium chloride.

3. An electroless nickel post dip according to claim 1, wherein: the palladium adsorbent is a polymerized product of acrylamide and dimethyl diallyl ammonium chloride.

4. An electroless nickel post dip according to claim 3, wherein: the molar ratio of the acrylamide or the maleic acid to the dimethyldiallylammonium chloride is 1: (1-3).

5. An electroless nickel post-dip according to any one of claims 1 to 4, wherein: the preparation method of the palladium adsorbent comprises the following steps:

Mixing acrylamide or maleic acid with cationic quaternary ammonium salt monomer, regulating pH to 7,

And adding ammonium persulfate-sodium bisulphite redox initiator to initiate polymerization.

6. An electroless nickel post dip according to claim 5, wherein: in the polymerization process, the reaction temperature is controlled at 75-80 ℃ and the reaction time is controlled at 20-30h.

7. An electroless nickel post dip according to claim 5, wherein: in the ammonium persulfate-sodium bisulphite redox initiator, the weight ratio of the ammonium persulfate to the sodium bisulphite is (1.5-2) 1.

8. A method of preparing an electroless nickel post-dip according to any one of claims 1 to 7, comprising the steps of:

Slowly adding sulfuric acid into deionized water, stirring uniformly, cooling to 20-35 ℃, adding palladium adsorbent, and stirring uniformly to obtain the post-leaching agent.

9. Use of an electroless nickel post dip according to any one of claims 1 to 7, characterized in that: is used in the post-dipping step of the electroless nickel palladium-gold plating process.

10. Use of an electroless nickel post dip according to claim 9, wherein: the post-soaking temperature of the post-soaking step is controlled at 15-35 ℃ and the soaking time is 1-5min.