Chemical nickel-palladium-gold post-plating agent and its preparation method and application

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 additives. The chemical nickel plating post-immersion agent includes 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. The post-immersion agent of the present application can effectively remove the Pd that is difficult to remove within the small line width and line spacing of the IC carrier. 2+ , solve the problem of easy gold penetration of IC substrate and improve product yield.

Description

Technical Field

[0001] 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

[0002] 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 the post-immersion agent.

[0003] 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

[0004] 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.

[0005] In the first aspect, the present application provides a chemical nickel plating post-immersion agent using the following technical solution:

[0006] 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.

[0007] In the present application, the post-chemical nickel plating immersion agent includes sulfuric acid and a palladium adsorbent. The sulfuric acid can quickly remove the Pd on the IC substrate surface. 2+ After cleaning, 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 20μm, and adsorb the Pd remaining in the tiny line width and line spacing of the IC substrate after the activation step. 2+ At the same time, under the action of sulfuric acid, the palladium adsorbent is easily removed by water washing, and no new residue is introduced to the IC substrate, which is beneficial to prevent the Pd 2+ It can also prevent the gold seepage problem caused by palladium adsorbent residue and other product quality problems caused by palladium adsorbent residue.

[0008] In addition, compared with the use of palladium adsorbent alone as a post-immersion agent, sulfuric acid combined with palladium adsorbent can effectively remove the Pd that is difficult to remove within the small line width and line spacing of the IC substrate. 2+ , solve the problem of easy gold penetration of IC substrates and improve product yield. At the same time, it can also reduce the cost of chemical nickel-palladium-gold plating process, without causing palladium adsorbent residue, and has more economic and practical value.

[0009] 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.

[0010] Preferably, the cationic quaternary ammonium salt monomer is dimethyldiallylammonium chloride.

[0011] In the present application, when the cationic monomer is dimethyldiallylammonium chloride, the palladium adsorbent is 2+ The adsorption stability is better, and the Pd encapsulated in the palladium adsorbent 2+ It is not easy to transfer back to the post-immersion agent. After obvious solid suspended matter appears in the post-immersion agent, it can be recycled after filtering to remove the solid suspended matter. 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.

[0012] Preferably, the molar ratio of acrylamide or maleic acid to dimethyldiallylammonium chloride is 1:(1-3).

[0013] 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 of the palladium adsorbent and the adsorption of Pd 2+ The effect is stronger, not only can it further quickly remove the residual Pd in ​​the small line width and line spacing of the IC substrate 2+ , and the Pd contained in the palladium adsorbent 2+ It is not easy to transfer back to the post-immersion agent. After obvious solid suspended matter appears in the post-immersion agent, it can be recycled after filtering to remove the solid suspended matter. 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.

[0014] More preferably, the molar ratio of acrylamide or maleic acid to dimethyldiallylammonium chloride is 1:2.

[0015] Preferably, the preparation method of the palladium adsorbent is as follows:

[0016] Mix acrylamide or maleic acid with cationic quaternary ammonium salt monomer, and then adjust the pH to 7.

[0017] The obtained product is obtained by adding ammonium persulfate-sodium bisulfite redox initiator to initiate polymerization.

[0018] In the present application, the above scheme can be used to produce a Pd substrate having excellent penetration effect, which can smoothly enter and exit the tiny line width and line spacing of less than 20 μm on the IC substrate, and adsorb the Pd remaining in the tiny line width and line spacing after the activation step. 2+ Palladium adsorbent.

[0019] Preferably, during the polymerization process, the reaction temperature is controlled at 75-80° C., and the reaction time is controlled at 20-30 h.

[0020] 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.

[0021] Optionally, in the ammonium persulfate-sodium bisulfite redox initiator, the weight ratio of ammonium persulfate to sodium bisulfite is (1.5-2):1.

[0022] In the second aspect, the present application provides a method for preparing a chemical nickel plating post-immersion agent using the following technical solution:

[0023] A method for preparing a chemical nickel plating post-immersion agent comprises the following steps:

[0024] 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.

[0025] In this 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, affecting the post-immersion agent on the residual Pd in ​​the small line width and line spacing of less than 20μm on the IC substrate. 2+ removal effect.

[0026] In a third aspect, the application of a chemical nickel plating post-immersion agent provided by the present application adopts the following technical solution:

[0027] 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.

[0028] In the present application, the 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 on the IC substrate. 2+ The post-immersion agent is effective for residual Pd in ​​the micro line width and line spacing of less than 20μm. 2+ It can also achieve excellent removal effect and prevent Pd on IC substrate 2+ The problem of gold seepage caused by residue.

[0029] 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.

[0030] 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.

[0031] In summary, the technical solution of the present application has the following beneficial effects:

[0032] (1) In the present application, the post-chemical nickel plating immersion agent includes sulfuric acid and a palladium adsorbent. The sulfuric acid can quickly remove the Pd on the surface of the IC substrate. 2+ After cleaning, 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 20μm, and adsorb the Pd remaining in the tiny line width and line spacing of the IC substrate after the activation step. 2+ At the same time, under the action of sulfuric acid, the palladium adsorbent is easily removed by water washing, and no new residue is introduced to the IC substrate, which is beneficial to prevent the Pd 2+ It can also prevent the gold seepage problem caused by palladium adsorbent residue and other product quality problems caused by palladium adsorbent residue.

[0033] In addition, compared with the use of palladium adsorbent alone as a post-immersion agent, sulfuric acid combined with palladium adsorbent can effectively remove the Pd that is difficult to remove within the small line width and line spacing of the IC substrate. 2+ , solve the problem of easy gold penetration of IC substrates and improve product yield. At the same time, it can also reduce the cost of chemical nickel-palladium-gold plating process, without causing palladium adsorbent residue, and has more economic and practical value.

[0034] (2) In this application, when the cationic monomer is dimethyldiallyl ammonium chloride, the palladium adsorbent is 2+ The adsorption stability is better, and the Pd encapsulated in the palladium adsorbent 2+ It is not easy to transfer back to the post-immersion agent. After obvious solid suspended matter appears in the post-immersion agent, it can be recycled after filtering to remove the solid suspended matter. 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a product picture of an IC substrate with a line width and line spacing of less than 10-20μm and no gold penetration.

[0036] Figure 2 This is a product picture of gold penetration on an IC substrate with a line width and line spacing of less than 10-20μm. DETAILED DESCRIPTION

[0037] The present application is further described below based on specific experiments. Example

[0038] [Example 1]

[0039] 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.

[0040] The preparation method of the post-infusion comprises the following steps:

[0041] 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 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 with a mass concentration of 1% and 0.15 kg of an aqueous solution of sodium bisulfite with a mass concentration of 0.5%, add them within 5 minutes, then raise the temperature to 75°C, react for 30 hours, discharge the material, and obtain a palladium adsorbent;

[0042] Sulfuric acid was slowly added to deionized water, stirred evenly, cooled to 20°C, and then palladium adsorbent was added, stirred evenly, to obtain a post-immersion agent.

[0043] [Example 2]

[0044] 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.

[0045] The preparation method of the post-infusion comprises the following steps:

[0046] 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 with a mass concentration of 1% and 0.15 kg of an aqueous solution of sodium bisulfite with a mass concentration of 0.5%, add them within 5 minutes, then raise the temperature to 80°C, react for 25 hours, discharge the material, and obtain a palladium adsorbent;

[0047] Sulfuric acid was slowly added to deionized water, stirred evenly, cooled to 20°C, and then palladium adsorbent was added, stirred evenly, to obtain a post-immersion agent.

[0048] [Example 3]

[0049] A post-immersion 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.

[0050] [Example 4]

[0051] 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.

[0052] Comparative Example

[0053] [Comparative Example 1]

[0054] A post-infusion agent, which differs from [Example 1] in that dimethyldiallylammonium chloride is replaced by an equimolar amount of acrylamide.

[0055] [Comparative Example 2]

[0056] A post-infusion agent, which differs from Example 2 in that dimethyldiallylammonium chloride is replaced by maleic acid in an equal molar amount.

[0057] [Comparative Example 3]

[0058] A post-immersion agent, which differs from [Example 1] in that acrylamide is replaced by an equimolar amount of dimethyldiallylammonium chloride.

[0059] Application Examples

[0060]

Application Example 1

[0061] The chemical nickel-palladium-gold plating process for IC substrates includes the following steps:

[0062] Step (1) sandblasting: sandblasting the IC substrate;

[0063] Step (2) Degreasing: Use S-31 acid degreasing agent to clean the printed circuit board for 5 minutes, and then wash with water;

[0064] Step (3) micro-etching: immerse the IC substrate treated in step (2) in a micro-etching solution for 2 minutes, and then rinse 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;

[0065] Step (4) pickling: immerse the IC substrate treated in step (3) in a 100 g / L sulfuric acid solution for 3 min, and then rinse with water;

[0066] Step (5) acid pre-immersion: immerse the IC substrate treated in step (4) in a 50 g / L sulfuric acid solution for 2 min;

[0067] 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;

[0068] 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 rinse with water;

[0069] 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;

[0070] 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.

[0071] Step (10) chemical gold plating: the IC substrate treated in step (9) is immersed in a reduction-type chemical gold plating solution of Smet SKG-22, the plating time is 20 minutes, the temperature is 80°C, and a chemical nickel-palladium-gold plated IC substrate is obtained.

[0072]

Application Example 2

[0073] 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].

[0074]

Application Example 3

[0075] The chemical nickel-palladium-gold plating process for IC substrates differs from that in [Application Example 1] in that the post-immersion agent in step (7) adopts the post-immersion agent prepared in [Example 3].

[0076]

Application example 4

[0077] The chemical nickel-palladium-gold plating process for IC substrates differs from that in [Application Example 1] in that the post-immersion agent in step (7) adopts the post-immersion agent prepared in [Example 4].

[0078] Comparative Application Examples

[0079]

Comparative Application Example 1

[0080] The chemical nickel-palladium-gold plating process for IC substrates differs from that in [Application Example 1] in that the post-immersion agent in step (7) adopts the post-immersion agent prepared in [Comparative Example 1].

[0081]

Comparative Application Example 2

[0082] The chemical nickel-palladium-gold plating process for IC substrates differs from that in [Application Example 1] in that the post-immersion agent in step (7) adopts the post-immersion agent prepared in [Comparative Example 2].

[0083]

Comparative Application Example 3

[0084] The chemical nickel-palladium-gold plating process for IC substrates differs from that in [Application Example 1] in that the post-immersion agent in step (7) adopts the post-immersion agent prepared in [Comparative Example 3].

[0085]

Comparative Application Example 4

[0086] The chemical nickel-palladium-gold plating process for IC substrates differs from that in [Application Example 1] in that the post-immersion agent in step (7) is replaced by a sulfuric acid solution with a mass concentration of 1%.

[0087] Performance testing

[0088] 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.

[0089] Table 1

[0090]

[0091] 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.

[0092] 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 less than 20μm.

[0093] 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.

[0094] 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 monomer, it can effectively remove the Pd that is difficult to remove within the small line width and line spacing of the IC substrate. 2+, solve the problem of easy gold penetration of IC substrate and improve product yield.

[0095] 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

1. A chemical nickel-palladium-gold post-immersion agent, characterized in that: It 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; The cationic quaternary ammonium salt monomer is at least one of dimethyldiallylammonium chloride and (4-ethoxy-2-hydroxy-4-oxobut-2-enyl)trimethylammonium chloride; The molar ratio of acrylamide or maleic acid to the cationic quaternary ammonium salt monomer is 1: (1-3); 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. An ammonium persulfate-sodium bisulfite redox initiator is added to initiate polymerization, during which the reaction temperature is controlled at 75-80° C. and the reaction time is controlled at 20-30 hours. In the ammonium persulfate-sodium bisulfite redox initiator, the weight ratio of ammonium persulfate to sodium bisulfite is (1.5-2):

1.

2. The method for preparing a chemical nickel-palladium-gold post-immersion agent according to claim 1, characterized in that: The following steps are involved: 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.

3. The use of a chemical nickel-palladium-gold post-immersion agent according to claim 1, characterized in that: Used in the post-immersion step of the chemical nickel-palladium-gold plating process.

4. The use of a chemical nickel-palladium-gold post-immersion agent according to claim 3, characterized in that: 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 minutes.

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